add: 04_I2C/06_编写APP直接访问EEPROM

IMX6ULL/doc_pic/04_I2C/06_编写APP直接访问EEPROM.md

@@ -0,0 +1,143 @@
+## 编写APP直接访问EEPROM
+
+参考资料：
+
+* Linux驱动程序: `drivers/i2c/i2c-dev.c`
+* I2C-Tools-4.2: `https://mirrors.edge.kernel.org/pub/software/utils/i2c-tools/`
+* AT24cxx.pdf
+
+本节源码：GIT仓库中
+
+* `doc_and_source_for_drivers\IMX6ULL\source\04_I2C\01_at24c02_test`
+* `doc_and_source_for_drivers\STM32MP157\source\A7\04_I2C\01_at24c02_test`
+
+### 1. 硬件连接
+
+* STM32MP157的I2C模块连接方法
+  ![image-20210225170942275](pic/04_I2C/036_stm32mp157_with_i2c_module.png)
+
+* IMX6ULL的I2C模块连接方法
+  ![image-20210225171500459](pic/04_I2C/037_imx6ull_with_i2c_module.png)
+
+
+
+### 2. AT24C02访问方法
+
+#### 2.1 设备地址
+
+从芯片手册上可以知道，AT24C02的设备地址跟它的A2、A1、A0引脚有关：
+
+![image-20210225173113723](pic/04_I2C/038_at24c02_device_address.png)
+
+打开I2C模块的原理图(这2个文件是一样的)：
+
+* `STM32MP157\开发板配套资料\原理图\04_Extend_modules(外设模块)\eeprom.zip\i2c_eeprom_module_v1.0.pdf`
+* `IMX6ULL\开发板配套资料\原理图\Extend_modules\eeprom.zip\i2c_eeprom_module_v1.0.pdf`
+* 如下：
+  ![image-20210225173414072](pic/04_I2C/039_at24c02_sch.png)
+
+从原理图可知，A2A1A0都是0，所以AT24C02的设备地址是：0b1010000，即0x50。
+
+
+
+
+
+#### 2.2 写数据
+
+![image-20210225173850025](pic/04_I2C/040_at24c02_byte_write.png)
+
+
+
+#### 2.3 读数据
+
+可以读1个字节，也可以连续读出多个字节。
+连续读多个字节时，芯片内部的地址会自动累加。
+当地址到达存储空间最后一个地址时，会从0开始。
+
+![image-20210225173934939](pic/04_I2C/041_at24c02_byte_read.png)
+
+### 3. 使用I2C-Tools的函数编程
+
+
+
+### 4. 编译
+
+#### 4.1 在Ubuntu设置交叉编译工具链
+
+* STM32MP157
+
+  ```shell
+  export ARCH=arm
+  export CROSS_COMPILE=arm-buildroot-linux-gnueabihf-
+  export PATH=$PATH:/home/book/100ask_stm32mp157_pro-sdk/ToolChain/arm-buildroot-linux-gnueabihf_sdk-buildroot/bin
+  ```
+
+* IMX6ULL
+
+  ```shell
+  export ARCH=arm
+  export CROSS_COMPILE=arm-linux-gnueabihf-
+  export PATH=$PATH:/home/book/100ask_imx6ull-sdk/ToolChain/gcc-linaro-6.2.1-2016.11-x86_64_arm-linux-gnueabihf/bin
+  ```
+
+  
+
+#### 4.2 使用I2C-Tools的源码
+
+![image-20210225210415578](pic/04_I2C/044_use_file_from_i2c_tools.png)
+
+#### 4.3 编译
+
+为IMX6ULL编译时，有如下错误：
+![image-20210225205509383](pic/04_I2C/042_imx6ull_has_not_smbus.h.png)
+
+这是因为IMX6ULL的工具链自带的include目录中，没有smbus.h。
+
+需要我们自己提供这个头文件，解决方法：
+
+* 提供头文件：
+  ![image-20210225205724354](pic/04_I2C/043_copy_include_from_i2c_tools.png)
+
+* 修改Makefile指定头文件目录
+
+  ```shell
+  all:
+  	$(CROSS_COMPILE)gcc -I ./include -o at24c02_test at24c02_test.c i2cbusses.c smbus.c
+  	
+  ```
+
+  
+
+
+
+### 4.4 上机测试
+
+**以下命令在开发板中执行。**
+
+* 挂载NFS
+
+  * vmware使用NAT(假设windowsIP为192.168.1.100)
+
+    ```shell
+    [root@100ask:~]# mount -t nfs -o nolock,vers=3,port=2049,mountport=9999 
+    192.168.1.100:/home/book/nfs_rootfs /mnt
+    ```
+
+  * vmware使用桥接，或者不使用vmware而是直接使用服务器：假设Ubuntu IP为192.168.1.137
+
+    ```shell
+    [root@100ask:~]#  mount -t nfs -o nolock,vers=3 192.168.1.137:/home/book/nfs_rootfs /mnt
+    ```
+
+
+
+* 复制、执行程序
+
+  ```shell
+  [root@100ask:~]# cp /mnt/at24c02_test   /bin
+  [root@100ask:~]# at24c02_test 0 w www.100ask.net
+  [root@100ask:~]# at24c02_test 0 r
+get data: www.100ask.net
+  ```
+  
+  

IMX6ULL/source/04_I2C/01_at24c02_test/Makefile

@@ -0,0 +1,3 @@
+all:
+	$(CROSS_COMPILE)gcc -I ./include -o at24c02_test at24c02_test.c i2cbusses.c smbus.c
+	

IMX6ULL/source/04_I2C/01_at24c02_test/at24c02_test.c

@@ -0,0 +1,102 @@
+
+#include <sys/ioctl.h>
+#include <errno.h>
+#include <string.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <linux/i2c.h>
+#include <linux/i2c-dev.h>
+#include <i2c/smbus.h>
+#include "i2cbusses.h"
+#include <time.h>
+
+
+/* ./at24c02 <i2c_bus_number> w "100ask.taobao.com"
+ * ./at24c02 <i2c_bus_number> r
+ */
+
+int main(int argc, char **argv)
+{
+	unsigned char dev_addr = 0x50;
+	unsigned char mem_addr = 0;
+	unsigned char buf[32];
+
+	int file;
+	char filename[20];
+	unsigned char *str;
+
+	int ret;
+
+	struct timespec req;
+	
+	if (argc != 3 && argc != 4)
+	{
+		printf("Usage:\n");
+		printf("write eeprom: %s <i2c_bus_number> w string\n", argv[0]);
+		printf("read  eeprom: %s <i2c_bus_number> r\n", argv[0]);
+		return -1;
+	}
+
+	file = open_i2c_dev(argv[1][0]-'0', filename, sizeof(filename), 0);
+	if (file < 0)
+	{
+		printf("can't open %s\n", filename);
+		return -1;
+	}
+
+	if (set_slave_addr(file, dev_addr, 1))
+	{
+		printf("can't set_slave_addr\n");
+		return -1;
+	}
+
+	if (argv[2][0] == 'w')
+	{
+		// write str: argv[3]
+		str = argv[3];
+
+		req.tv_sec  = 0;
+		req.tv_nsec = 20000000; /* 20ms */
+		
+		while (*str)
+		{
+			// mem_addr, *str
+			// mem_addr++, str++
+			ret = i2c_smbus_write_byte_data(file, mem_addr, *str);
+			if (ret)
+			{
+				printf("i2c_smbus_write_byte_data err\n");
+				return -1;
+			}
+			// wait tWR(10ms)
+			nanosleep(&req, NULL);
+			
+			mem_addr++;
+			str++;
+		}
+		ret = i2c_smbus_write_byte_data(file, mem_addr, 0); // string end char
+		if (ret)
+		{
+			printf("i2c_smbus_write_byte_data err\n");
+			return -1;
+		}
+	}
+	else
+	{
+		// read
+		ret = i2c_smbus_read_i2c_block_data(file, mem_addr, sizeof(buf), buf);
+		if (ret < 0)
+		{
+			printf("i2c_smbus_read_i2c_block_data err\n");
+			return -1;
+		}
+		
+		buf[31] = '\0';
+		printf("get data: %s\n", buf);
+	}
+	
+	return 0;
+	
+}
+

IMX6ULL/source/04_I2C/01_at24c02_test/i2cbusses.c

@@ -0,0 +1,455 @@
+/*
+    i2cbusses: Print the installed i2c busses for both 2.4 and 2.6 kernels.
+               Part of user-space programs to access for I2C
+               devices.
+    Copyright (c) 1999-2003  Frodo Looijaard <frodol@dds.nl> and
+                             Mark D. Studebaker <mdsxyz123@yahoo.com>
+    Copyright (C) 2008-2012  Jean Delvare <jdelvare@suse.de>
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program; if not, write to the Free Software
+    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+    MA 02110-1301 USA.
+*/
+
+/* For strdup and snprintf */
+#define _BSD_SOURCE 1 /* for glibc <= 2.19 */
+#define _DEFAULT_SOURCE 1 /* for glibc >= 2.19 */
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/param.h>	/* for NAME_MAX */
+#include <sys/ioctl.h>
+#include <string.h>
+#include <strings.h>	/* for strcasecmp() */
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <limits.h>
+#include <dirent.h>
+#include <fcntl.h>
+#include <errno.h>
+#include "i2cbusses.h"
+#include <linux/i2c.h>
+#include <linux/i2c-dev.h>
+
+enum adt { adt_dummy, adt_isa, adt_i2c, adt_smbus, adt_unknown };
+
+struct adap_type {
+	const char *funcs;
+	const char* algo;
+};
+
+static struct adap_type adap_types[5] = {
+	{ .funcs	= "dummy",
+	  .algo		= "Dummy bus", },
+	{ .funcs	= "isa",
+	  .algo		= "ISA bus", },
+	{ .funcs	= "i2c",
+	  .algo		= "I2C adapter", },
+	{ .funcs	= "smbus",
+	  .algo		= "SMBus adapter", },
+	{ .funcs	= "unknown",
+	  .algo		= "N/A", },
+};
+
+static enum adt i2c_get_funcs(int i2cbus)
+{
+	unsigned long funcs;
+	int file;
+	char filename[20];
+	enum adt ret;
+
+	file = open_i2c_dev(i2cbus, filename, sizeof(filename), 1);
+	if (file < 0)
+		return adt_unknown;
+
+	if (ioctl(file, I2C_FUNCS, &funcs) < 0)
+		ret = adt_unknown;
+	else if (funcs & I2C_FUNC_I2C)
+		ret = adt_i2c;
+	else if (funcs & (I2C_FUNC_SMBUS_BYTE |
+			  I2C_FUNC_SMBUS_BYTE_DATA |
+			  I2C_FUNC_SMBUS_WORD_DATA))
+		ret = adt_smbus;
+	else
+		ret = adt_dummy;
+
+	close(file);
+	return ret;
+}
+
+/* Remove trailing spaces from a string
+   Return the new string length including the trailing NUL */
+static int rtrim(char *s)
+{
+	int i;
+
+	for (i = strlen(s) - 1; i >= 0 && (s[i] == ' ' || s[i] == '\n'); i--)
+		s[i] = '\0';
+	return i + 2;
+}
+
+void free_adapters(struct i2c_adap *adapters)
+{
+	int i;
+
+	for (i = 0; adapters[i].name; i++)
+		free(adapters[i].name);
+	free(adapters);
+}
+
+/* We allocate space for the adapters in bunches. The last item is a
+   terminator, so here we start with room for 7 adapters, which should
+   be enough in most cases. If not, we allocate more later as needed. */
+#define BUNCH	8
+
+/* n must match the size of adapters at calling time */
+static struct i2c_adap *more_adapters(struct i2c_adap *adapters, int n)
+{
+	struct i2c_adap *new_adapters;
+
+	new_adapters = realloc(adapters, (n + BUNCH) * sizeof(struct i2c_adap));
+	if (!new_adapters) {
+		free_adapters(adapters);
+		return NULL;
+	}
+	memset(new_adapters + n, 0, BUNCH * sizeof(struct i2c_adap));
+
+	return new_adapters;
+}
+
+struct i2c_adap *gather_i2c_busses(void)
+{
+	char s[120];
+	struct dirent *de, *dde;
+	DIR *dir, *ddir;
+	FILE *f;
+	char fstype[NAME_MAX], sysfs[NAME_MAX], n[NAME_MAX];
+	int foundsysfs = 0;
+	int len, count = 0;
+	struct i2c_adap *adapters;
+
+	adapters = calloc(BUNCH, sizeof(struct i2c_adap));
+	if (!adapters)
+		return NULL;
+
+	/* look in /proc/bus/i2c */
+	if ((f = fopen("/proc/bus/i2c", "r"))) {
+		while (fgets(s, 120, f)) {
+			char *algo, *name, *type, *all;
+			int len_algo, len_name, len_type;
+			int i2cbus;
+
+			algo = strrchr(s, '\t');
+			*(algo++) = '\0';
+			len_algo = rtrim(algo);
+
+			name = strrchr(s, '\t');
+			*(name++) = '\0';
+			len_name = rtrim(name);
+
+			type = strrchr(s, '\t');
+			*(type++) = '\0';
+			len_type = rtrim(type);
+
+			sscanf(s, "i2c-%d", &i2cbus);
+
+			if ((count + 1) % BUNCH == 0) {
+				/* We need more space */
+				adapters = more_adapters(adapters, count + 1);
+				if (!adapters)
+					return NULL;
+			}
+
+			all = malloc(len_name + len_type + len_algo);
+			if (all == NULL) {
+				free_adapters(adapters);
+				return NULL;
+			}
+			adapters[count].nr = i2cbus;
+			adapters[count].name = strcpy(all, name);
+			adapters[count].funcs = strcpy(all + len_name, type);
+			adapters[count].algo = strcpy(all + len_name + len_type,
+						      algo);
+			count++;
+		}
+		fclose(f);
+		goto done;
+	}
+
+	/* look in sysfs */
+	/* First figure out where sysfs was mounted */
+	if ((f = fopen("/proc/mounts", "r")) == NULL) {
+		goto done;
+	}
+	while (fgets(n, NAME_MAX, f)) {
+		sscanf(n, "%*[^ ] %[^ ] %[^ ] %*s\n", sysfs, fstype);
+		if (strcasecmp(fstype, "sysfs") == 0) {
+			foundsysfs++;
+			break;
+		}
+	}
+	fclose(f);
+	if (! foundsysfs) {
+		goto done;
+	}
+
+	/* Bus numbers in i2c-adapter don't necessarily match those in
+	   i2c-dev and what we really care about are the i2c-dev numbers.
+	   Unfortunately the names are harder to get in i2c-dev */
+	strcat(sysfs, "/class/i2c-dev");
+	if(!(dir = opendir(sysfs)))
+		goto done;
+	/* go through the busses */
+	while ((de = readdir(dir)) != NULL) {
+		if (!strcmp(de->d_name, "."))
+			continue;
+		if (!strcmp(de->d_name, ".."))
+			continue;
+
+		/* this should work for kernels 2.6.5 or higher and */
+		/* is preferred because is unambiguous */
+		len = snprintf(n, NAME_MAX, "%s/%s/name", sysfs, de->d_name);
+		if (len >= NAME_MAX) {
+			fprintf(stderr, "%s: path truncated\n", n);
+			continue;
+		}
+		f = fopen(n, "r");
+		/* this seems to work for ISA */
+		if(f == NULL) {
+			len = snprintf(n, NAME_MAX, "%s/%s/device/name", sysfs,
+				       de->d_name);
+			if (len >= NAME_MAX) {
+				fprintf(stderr, "%s: path truncated\n", n);
+				continue;
+			}
+			f = fopen(n, "r");
+		}
+		/* non-ISA is much harder */
+		/* and this won't find the correct bus name if a driver
+		   has more than one bus */
+		if(f == NULL) {
+			len = snprintf(n, NAME_MAX, "%s/%s/device", sysfs,
+				       de->d_name);
+			if (len >= NAME_MAX) {
+				fprintf(stderr, "%s: path truncated\n", n);
+				continue;
+			}
+			if(!(ddir = opendir(n)))
+				continue;
+			while ((dde = readdir(ddir)) != NULL) {
+				if (!strcmp(dde->d_name, "."))
+					continue;
+				if (!strcmp(dde->d_name, ".."))
+					continue;
+				if ((!strncmp(dde->d_name, "i2c-", 4))) {
+					len = snprintf(n, NAME_MAX,
+						       "%s/%s/device/%s/name",
+						       sysfs, de->d_name,
+						       dde->d_name);
+					if (len >= NAME_MAX) {
+						fprintf(stderr,
+							"%s: path truncated\n",
+							n);
+						continue;
+					}
+					if((f = fopen(n, "r")))
+						goto found;
+				}
+			}
+		}
+
+found:
+		if (f != NULL) {
+			int i2cbus;
+			enum adt type;
+			char *px;
+
+			px = fgets(s, 120, f);
+			fclose(f);
+			if (!px) {
+				fprintf(stderr, "%s: read error\n", n);
+				continue;
+			}
+			if ((px = strchr(s, '\n')) != NULL)
+				*px = 0;
+			if (!sscanf(de->d_name, "i2c-%d", &i2cbus))
+				continue;
+			if (!strncmp(s, "ISA ", 4)) {
+				type = adt_isa;
+			} else {
+				/* Attempt to probe for adapter capabilities */
+				type = i2c_get_funcs(i2cbus);
+			}
+
+			if ((count + 1) % BUNCH == 0) {
+				/* We need more space */
+				adapters = more_adapters(adapters, count + 1);
+				if (!adapters)
+					return NULL;
+			}
+
+			adapters[count].nr = i2cbus;
+			adapters[count].name = strdup(s);
+			if (adapters[count].name == NULL) {
+				free_adapters(adapters);
+				return NULL;
+			}
+			adapters[count].funcs = adap_types[type].funcs;
+			adapters[count].algo = adap_types[type].algo;
+			count++;
+		}
+	}
+	closedir(dir);
+
+done:
+	return adapters;
+}
+
+static int lookup_i2c_bus_by_name(const char *bus_name)
+{
+	struct i2c_adap *adapters;
+	int i, i2cbus = -1;
+
+	adapters = gather_i2c_busses();
+	if (adapters == NULL) {
+		fprintf(stderr, "Error: Out of memory!\n");
+		return -3;
+	}
+
+	/* Walk the list of i2c busses, looking for the one with the
+	   right name */
+	for (i = 0; adapters[i].name; i++) {
+		if (strcmp(adapters[i].name, bus_name) == 0) {
+			if (i2cbus >= 0) {
+				fprintf(stderr,
+					"Error: I2C bus name is not unique!\n");
+				i2cbus = -4;
+				goto done;
+			}
+			i2cbus = adapters[i].nr;
+		}
+	}
+
+	if (i2cbus == -1)
+		fprintf(stderr, "Error: I2C bus name doesn't match any "
+			"bus present!\n");
+
+done:
+	free_adapters(adapters);
+	return i2cbus;
+}
+
+/*
+ * Parse an I2CBUS command line argument and return the corresponding
+ * bus number, or a negative value if the bus is invalid.
+ */
+int lookup_i2c_bus(const char *i2cbus_arg)
+{
+	unsigned long i2cbus;
+	char *end;
+
+	i2cbus = strtoul(i2cbus_arg, &end, 0);
+	if (*end || !*i2cbus_arg) {
+		/* Not a number, maybe a name? */
+		return lookup_i2c_bus_by_name(i2cbus_arg);
+	}
+	if (i2cbus > 0xFFFFF) {
+		fprintf(stderr, "Error: I2C bus out of range!\n");
+		return -2;
+	}
+
+	return i2cbus;
+}
+
+/*
+ * Parse a CHIP-ADDRESS command line argument and return the corresponding
+ * chip address, or a negative value if the address is invalid.
+ */
+int parse_i2c_address(const char *address_arg, int all_addrs)
+{
+	long address;
+	char *end;
+	long min_addr = 0x08;
+	long max_addr = 0x77;
+
+	address = strtol(address_arg, &end, 0);
+	if (*end || !*address_arg) {
+		fprintf(stderr, "Error: Chip address is not a number!\n");
+		return -1;
+	}
+
+	if (all_addrs) {
+		min_addr = 0x00;
+		max_addr = 0x7f;
+	}
+
+	if (address < min_addr || address > max_addr) {
+		fprintf(stderr, "Error: Chip address out of range "
+			"(0x%02lx-0x%02lx)!\n", min_addr, max_addr);
+		return -2;
+	}
+
+	return address;
+}
+
+int open_i2c_dev(int i2cbus, char *filename, size_t size, int quiet)
+{
+	int file, len;
+
+	len = snprintf(filename, size, "/dev/i2c/%d", i2cbus);
+	if (len >= (int)size) {
+		fprintf(stderr, "%s: path truncated\n", filename);
+		return -EOVERFLOW;
+	}
+	file = open(filename, O_RDWR);
+
+	if (file < 0 && (errno == ENOENT || errno == ENOTDIR)) {
+		len = snprintf(filename, size, "/dev/i2c-%d", i2cbus);
+		if (len >= (int)size) {
+			fprintf(stderr, "%s: path truncated\n", filename);
+			return -EOVERFLOW;
+		}
+		file = open(filename, O_RDWR);
+	}
+
+	if (file < 0 && !quiet) {
+		if (errno == ENOENT) {
+			fprintf(stderr, "Error: Could not open file "
+				"`/dev/i2c-%d' or `/dev/i2c/%d': %s\n",
+				i2cbus, i2cbus, strerror(ENOENT));
+		} else {
+			fprintf(stderr, "Error: Could not open file "
+				"`%s': %s\n", filename, strerror(errno));
+			if (errno == EACCES)
+				fprintf(stderr, "Run as root?\n");
+		}
+	}
+
+	return file;
+}
+
+int set_slave_addr(int file, int address, int force)
+{
+	/* With force, let the user read from/write to the registers
+	   even when a driver is also running */
+	if (ioctl(file, force ? I2C_SLAVE_FORCE : I2C_SLAVE, address) < 0) {
+		fprintf(stderr,
+			"Error: Could not set address to 0x%02x: %s\n",
+			address, strerror(errno));
+		return -errno;
+	}
+
+	return 0;
+}

IMX6ULL/source/04_I2C/01_at24c02_test/i2cbusses.h

@@ -0,0 +1,44 @@
+/*
+    i2cbusses.h - Part of the i2c-tools package
+
+    Copyright (C) 2004-2010  Jean Delvare <jdelvare@suse.de>
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program; if not, write to the Free Software
+    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+    MA 02110-1301 USA.
+*/
+
+#ifndef _I2CBUSSES_H
+#define _I2CBUSSES_H
+
+#include <unistd.h>
+
+struct i2c_adap {
+	int nr;
+	char *name;
+	const char *funcs;
+	const char *algo;
+};
+
+struct i2c_adap *gather_i2c_busses(void);
+void free_adapters(struct i2c_adap *adapters);
+
+int lookup_i2c_bus(const char *i2cbus_arg);
+int parse_i2c_address(const char *address_arg, int all_addrs);
+int open_i2c_dev(int i2cbus, char *filename, size_t size, int quiet);
+int set_slave_addr(int file, int address, int force);
+
+#define MISSING_FUNC_FMT	"Error: Adapter does not have %s capability\n"
+
+#endif

IMX6ULL/source/04_I2C/01_at24c02_test/include/i2c/smbus.h

@@ -0,0 +1,52 @@
+/*
+    smbus.h - SMBus level access helper functions
+
+    Copyright (C) 1995-1997  Simon G. Vogl
+    Copyright (C) 1998-1999  Frodo Looijaard <frodol@dds.nl>
+    Copyright (C) 2012-2017  Jean Delvare <jdelvare@suse.de>
+
+    This library is free software; you can redistribute it and/or modify
+    it under the terms of the GNU Lesser General Public License as published
+    by the Free Software Foundation; either version 2.1 of the License, or
+    (at your option) any later version.
+*/
+
+#ifndef LIB_I2C_SMBUS_H
+#define LIB_I2C_SMBUS_H
+
+#define I2C_API_VERSION		0x100
+
+#include <linux/types.h>
+#include <linux/i2c.h>
+
+extern __s32 i2c_smbus_access(int file, char read_write, __u8 command,
+			      int size, union i2c_smbus_data *data);
+
+extern __s32 i2c_smbus_write_quick(int file, __u8 value);
+extern __s32 i2c_smbus_read_byte(int file);
+extern __s32 i2c_smbus_write_byte(int file, __u8 value);
+extern __s32 i2c_smbus_read_byte_data(int file, __u8 command);
+extern __s32 i2c_smbus_write_byte_data(int file, __u8 command, __u8 value);
+extern __s32 i2c_smbus_read_word_data(int file, __u8 command);
+extern __s32 i2c_smbus_write_word_data(int file, __u8 command, __u16 value);
+extern __s32 i2c_smbus_process_call(int file, __u8 command, __u16 value);
+
+/* Returns the number of read bytes */
+extern __s32 i2c_smbus_read_block_data(int file, __u8 command, __u8 *values);
+extern __s32 i2c_smbus_write_block_data(int file, __u8 command, __u8 length,
+					const __u8 *values);
+
+/* Returns the number of read bytes */
+/* Until kernel 2.6.22, the length is hardcoded to 32 bytes. If you
+   ask for less than 32 bytes, your code will only work with kernels
+   2.6.23 and later. */
+extern __s32 i2c_smbus_read_i2c_block_data(int file, __u8 command, __u8 length,
+					   __u8 *values);
+extern __s32 i2c_smbus_write_i2c_block_data(int file, __u8 command, __u8 length,
+					    const __u8 *values);
+
+/* Returns the number of read bytes */
+extern __s32 i2c_smbus_block_process_call(int file, __u8 command, __u8 length,
+					  __u8 *values);
+
+#endif /* LIB_I2C_SMBUS_H */

IMX6ULL/source/04_I2C/01_at24c02_test/smbus.c

@@ -0,0 +1,214 @@
+/*
+    smbus.c - SMBus level access helper functions
+
+    Copyright (C) 1995-1997  Simon G. Vogl
+    Copyright (C) 1998-1999  Frodo Looijaard <frodol@dds.nl>
+    Copyright (C) 2012-2013  Jean Delvare <jdelvare@suse.de>
+
+    This library is free software; you can redistribute it and/or modify
+    it under the terms of the GNU Lesser General Public License as published
+    by the Free Software Foundation; either version 2.1 of the License, or
+    (at your option) any later version.
+*/
+
+#include <errno.h>
+#include <stddef.h>
+#include <i2c/smbus.h>
+#include <sys/ioctl.h>
+#include <linux/types.h>
+#include <linux/i2c.h>
+#include <linux/i2c-dev.h>
+
+/* Compatibility defines */
+#ifndef I2C_SMBUS_I2C_BLOCK_BROKEN
+#define I2C_SMBUS_I2C_BLOCK_BROKEN I2C_SMBUS_I2C_BLOCK_DATA
+#endif
+#ifndef I2C_FUNC_SMBUS_PEC
+#define I2C_FUNC_SMBUS_PEC I2C_FUNC_SMBUS_HWPEC_CALC
+#endif
+
+__s32 i2c_smbus_access(int file, char read_write, __u8 command,
+		       int size, union i2c_smbus_data *data)
+{
+	struct i2c_smbus_ioctl_data args;
+	__s32 err;
+
+	args.read_write = read_write;
+	args.command = command;
+	args.size = size;
+	args.data = data;
+
+	err = ioctl(file, I2C_SMBUS, &args);
+	if (err == -1)
+		err = -errno;
+	return err;
+}
+
+
+__s32 i2c_smbus_write_quick(int file, __u8 value)
+{
+	return i2c_smbus_access(file, value, 0, I2C_SMBUS_QUICK, NULL);
+}
+
+__s32 i2c_smbus_read_byte(int file)
+{
+	union i2c_smbus_data data;
+	int err;
+
+	err = i2c_smbus_access(file, I2C_SMBUS_READ, 0, I2C_SMBUS_BYTE, &data);
+	if (err < 0)
+		return err;
+
+	return 0x0FF & data.byte;
+}
+
+__s32 i2c_smbus_write_byte(int file, __u8 value)
+{
+	return i2c_smbus_access(file, I2C_SMBUS_WRITE, value,
+				I2C_SMBUS_BYTE, NULL);
+}
+
+__s32 i2c_smbus_read_byte_data(int file, __u8 command)
+{
+	union i2c_smbus_data data;
+	int err;
+
+	err = i2c_smbus_access(file, I2C_SMBUS_READ, command,
+			       I2C_SMBUS_BYTE_DATA, &data);
+	if (err < 0)
+		return err;
+
+	return 0x0FF & data.byte;
+}
+
+__s32 i2c_smbus_write_byte_data(int file, __u8 command, __u8 value)
+{
+	union i2c_smbus_data data;
+	data.byte = value;
+	return i2c_smbus_access(file, I2C_SMBUS_WRITE, command,
+				I2C_SMBUS_BYTE_DATA, &data);
+}
+
+__s32 i2c_smbus_read_word_data(int file, __u8 command)
+{
+	union i2c_smbus_data data;
+	int err;
+
+	err = i2c_smbus_access(file, I2C_SMBUS_READ, command,
+			       I2C_SMBUS_WORD_DATA, &data);
+	if (err < 0)
+		return err;
+
+	return 0x0FFFF & data.word;
+}
+
+__s32 i2c_smbus_write_word_data(int file, __u8 command, __u16 value)
+{
+	union i2c_smbus_data data;
+	data.word = value;
+	return i2c_smbus_access(file, I2C_SMBUS_WRITE, command,
+				I2C_SMBUS_WORD_DATA, &data);
+}
+
+__s32 i2c_smbus_process_call(int file, __u8 command, __u16 value)
+{
+	union i2c_smbus_data data;
+	data.word = value;
+	if (i2c_smbus_access(file, I2C_SMBUS_WRITE, command,
+			     I2C_SMBUS_PROC_CALL, &data))
+		return -1;
+	else
+		return 0x0FFFF & data.word;
+}
+
+/* Returns the number of read bytes */
+__s32 i2c_smbus_read_block_data(int file, __u8 command, __u8 *values)
+{
+	union i2c_smbus_data data;
+	int i, err;
+
+	err = i2c_smbus_access(file, I2C_SMBUS_READ, command,
+			       I2C_SMBUS_BLOCK_DATA, &data);
+	if (err < 0)
+		return err;
+
+	for (i = 1; i <= data.block[0]; i++)
+		values[i-1] = data.block[i];
+	return data.block[0];
+}
+
+__s32 i2c_smbus_write_block_data(int file, __u8 command, __u8 length,
+				 const __u8 *values)
+{
+	union i2c_smbus_data data;
+	int i;
+	if (length > I2C_SMBUS_BLOCK_MAX)
+		length = I2C_SMBUS_BLOCK_MAX;
+	for (i = 1; i <= length; i++)
+		data.block[i] = values[i-1];
+	data.block[0] = length;
+	return i2c_smbus_access(file, I2C_SMBUS_WRITE, command,
+				I2C_SMBUS_BLOCK_DATA, &data);
+}
+
+/* Returns the number of read bytes */
+/* Until kernel 2.6.22, the length is hardcoded to 32 bytes. If you
+   ask for less than 32 bytes, your code will only work with kernels
+   2.6.23 and later. */
+__s32 i2c_smbus_read_i2c_block_data(int file, __u8 command, __u8 length,
+				    __u8 *values)
+{
+	union i2c_smbus_data data;
+	int i, err;
+
+	if (length > I2C_SMBUS_BLOCK_MAX)
+		length = I2C_SMBUS_BLOCK_MAX;
+	data.block[0] = length;
+
+	err = i2c_smbus_access(file, I2C_SMBUS_READ, command,
+			       length == 32 ? I2C_SMBUS_I2C_BLOCK_BROKEN :
+				I2C_SMBUS_I2C_BLOCK_DATA, &data);
+	if (err < 0)
+		return err;
+
+	for (i = 1; i <= data.block[0]; i++)
+		values[i-1] = data.block[i];
+	return data.block[0];
+}
+
+__s32 i2c_smbus_write_i2c_block_data(int file, __u8 command, __u8 length,
+				     const __u8 *values)
+{
+	union i2c_smbus_data data;
+	int i;
+	if (length > I2C_SMBUS_BLOCK_MAX)
+		length = I2C_SMBUS_BLOCK_MAX;
+	for (i = 1; i <= length; i++)
+		data.block[i] = values[i-1];
+	data.block[0] = length;
+	return i2c_smbus_access(file, I2C_SMBUS_WRITE, command,
+				I2C_SMBUS_I2C_BLOCK_BROKEN, &data);
+}
+
+/* Returns the number of read bytes */
+__s32 i2c_smbus_block_process_call(int file, __u8 command, __u8 length,
+				   __u8 *values)
+{
+	union i2c_smbus_data data;
+	int i, err;
+
+	if (length > I2C_SMBUS_BLOCK_MAX)
+		length = I2C_SMBUS_BLOCK_MAX;
+	for (i = 1; i <= length; i++)
+		data.block[i] = values[i-1];
+	data.block[0] = length;
+
+	err = i2c_smbus_access(file, I2C_SMBUS_WRITE, command,
+			       I2C_SMBUS_BLOCK_PROC_CALL, &data);
+	if (err < 0)
+		return err;
+
+	for (i = 1; i <= data.block[0]; i++)
+		values[i-1] = data.block[i];
+	return data.block[0];
+}

README.md

@@ -85,10 +85,10 @@ git clone https://e.coding.net/weidongshan/doc_and_source_for_drivers.git
 * 2021.02.25 发布"I2C系统"：
 
   * 修改：03_SMBus协议，增加了I2C Block Read/Write
+* 新增：05\_无需编写驱动直接访问设备\_I2C-Tools介绍
+  * 新增：06_编写APP直接访问EEPROM
 
-  * 新增：05\_无需编写驱动直接访问设备\_I2C-Tools介绍
+  
-
-    
 
 ## 6. 联系方式
 

STM32MP157/doc_pic/04_I2C/03_SMBus协议.md

@@ -221,7 +221,41 @@ Functionality flag: I2C_FUNC_SMBUS_WRITE_BLOCK_DATA
 
 
 
-#### 2.11 SMBus Block Write - Block Read Process Call
+#### 2.11 I2C Block Read
+
+在一般的I2C协议中，也可以连续读出多个字节。
+它跟`SMBus Block Read`的差别在于设备发出的第1个数据不是长度N，如下图所示：
+
+![image-20210225094024082](pic/04_I2C/033_i2c_block_read.png)
+
+I2C-tools中的函数：i2c_smbus_read_i2c_block_data()。
+
+先发出`Command Code`(它一般表示芯片内部的寄存器地址)，再发出1个字节的`Byte Conut`(表示后续要发出的数据字节数)，最后发出全部数据。
+
+```shell
+Functionality flag: I2C_FUNC_SMBUS_READ_I2C_BLOCK
+```
+
+
+
+#### 2.12 I2C Block Write
+
+在一般的I2C协议中，也可以连续发出多个字节。
+它跟`SMBus Block Write`的差别在于发出的第1个数据不是长度N，如下图所示：
+
+![image-20210225094359443](pic/04_I2C/034_i2c_block_write.png)
+
+I2C-tools中的函数：i2c_smbus_write_i2c_block_data()。
+
+先发出`Command Code`(它一般表示芯片内部的寄存器地址)，再发出1个字节的`Byte Conut`(表示后续要发出的数据字节数)，最后发出全部数据。
+
+```shell
+Functionality flag: I2C_FUNC_SMBUS_WRITE_I2C_BLOCK
+```
+
+
+
+#### 2.13 SMBus Block Write - Block Read Process Call
 
 ![image-20210224112940865](pic/04_I2C/028_smbus_block_write_block_read_process_call.png)先写一块数据，再读一块数据。
 
@@ -231,7 +265,7 @@ Functionality flag: I2C_FUNC_SMBUS_BLOCK_PROC_CALL
 
 
 
-#### 2.12 Packet Error Checking (PEC)
+#### 2.14 Packet Error Checking (PEC)
 
 PEC是一种错误校验码，如果使用PEC，那么在P信号之前，数据发送方要发送一个字节的PEC码(它是CRC-8码)。
 

STM32MP157/doc_pic/04_I2C/06_编写APP直接访问EEPROM.md

@@ -0,0 +1,143 @@
+## 编写APP直接访问EEPROM
+
+参考资料：
+
+* Linux驱动程序: `drivers/i2c/i2c-dev.c`
+* I2C-Tools-4.2: `https://mirrors.edge.kernel.org/pub/software/utils/i2c-tools/`
+* AT24cxx.pdf
+
+本节源码：GIT仓库中
+
+* `doc_and_source_for_drivers\IMX6ULL\source\04_I2C\01_at24c02_test`
+* `doc_and_source_for_drivers\STM32MP157\source\A7\04_I2C\01_at24c02_test`
+
+### 1. 硬件连接
+
+* STM32MP157的I2C模块连接方法
+  ![image-20210225170942275](pic/04_I2C/036_stm32mp157_with_i2c_module.png)
+
+* IMX6ULL的I2C模块连接方法
+  ![image-20210225171500459](pic/04_I2C/037_imx6ull_with_i2c_module.png)
+
+
+
+### 2. AT24C02访问方法
+
+#### 2.1 设备地址
+
+从芯片手册上可以知道，AT24C02的设备地址跟它的A2、A1、A0引脚有关：
+
+![image-20210225173113723](pic/04_I2C/038_at24c02_device_address.png)
+
+打开I2C模块的原理图(这2个文件是一样的)：
+
+* `STM32MP157\开发板配套资料\原理图\04_Extend_modules(外设模块)\eeprom.zip\i2c_eeprom_module_v1.0.pdf`
+* `IMX6ULL\开发板配套资料\原理图\Extend_modules\eeprom.zip\i2c_eeprom_module_v1.0.pdf`
+* 如下：
+  ![image-20210225173414072](pic/04_I2C/039_at24c02_sch.png)
+
+从原理图可知，A2A1A0都是0，所以AT24C02的设备地址是：0b1010000，即0x50。
+
+
+
+
+
+#### 2.2 写数据
+
+![image-20210225173850025](pic/04_I2C/040_at24c02_byte_write.png)
+
+
+
+#### 2.3 读数据
+
+可以读1个字节，也可以连续读出多个字节。
+连续读多个字节时，芯片内部的地址会自动累加。
+当地址到达存储空间最后一个地址时，会从0开始。
+
+![image-20210225173934939](pic/04_I2C/041_at24c02_byte_read.png)
+
+### 3. 使用I2C-Tools的函数编程
+
+
+
+### 4. 编译
+
+#### 4.1 在Ubuntu设置交叉编译工具链
+
+* STM32MP157
+
+  ```shell
+  export ARCH=arm
+  export CROSS_COMPILE=arm-buildroot-linux-gnueabihf-
+  export PATH=$PATH:/home/book/100ask_stm32mp157_pro-sdk/ToolChain/arm-buildroot-linux-gnueabihf_sdk-buildroot/bin
+  ```
+
+* IMX6ULL
+
+  ```shell
+  export ARCH=arm
+  export CROSS_COMPILE=arm-linux-gnueabihf-
+  export PATH=$PATH:/home/book/100ask_imx6ull-sdk/ToolChain/gcc-linaro-6.2.1-2016.11-x86_64_arm-linux-gnueabihf/bin
+  ```
+
+  
+
+#### 4.2 使用I2C-Tools的源码
+
+![image-20210225210415578](pic/04_I2C/044_use_file_from_i2c_tools.png)
+
+#### 4.3 编译
+
+为IMX6ULL编译时，有如下错误：
+![image-20210225205509383](pic/04_I2C/042_imx6ull_has_not_smbus.h.png)
+
+这是因为IMX6ULL的工具链自带的include目录中，没有smbus.h。
+
+需要我们自己提供这个头文件，解决方法：
+
+* 提供头文件：
+  ![image-20210225205724354](pic/04_I2C/043_copy_include_from_i2c_tools.png)
+
+* 修改Makefile指定头文件目录
+
+  ```shell
+  all:
+  	$(CROSS_COMPILE)gcc -I ./include -o at24c02_test at24c02_test.c i2cbusses.c smbus.c
+  	
+  ```
+
+  
+
+
+
+### 4.4 上机测试
+
+**以下命令在开发板中执行。**
+
+* 挂载NFS
+
+  * vmware使用NAT(假设windowsIP为192.168.1.100)
+
+    ```shell
+    [root@100ask:~]# mount -t nfs -o nolock,vers=3,port=2049,mountport=9999 
+    192.168.1.100:/home/book/nfs_rootfs /mnt
+    ```
+
+  * vmware使用桥接，或者不使用vmware而是直接使用服务器：假设Ubuntu IP为192.168.1.137
+
+    ```shell
+    [root@100ask:~]#  mount -t nfs -o nolock,vers=3 192.168.1.137:/home/book/nfs_rootfs /mnt
+    ```
+
+
+
+* 复制、执行程序
+
+  ```shell
+  [root@100ask:~]# cp /mnt/at24c02_test   /bin
+  [root@100ask:~]# at24c02_test 0 w www.100ask.net
+  [root@100ask:~]# at24c02_test 0 r
+get data: www.100ask.net
+  ```
+  
+  

STM32MP157/source/A7/04_I2C/01_at24c02_test/Makefile

@@ -0,0 +1,3 @@
+all:
+	$(CROSS_COMPILE)gcc -I ./include -o at24c02_test at24c02_test.c i2cbusses.c smbus.c
+	

STM32MP157/source/A7/04_I2C/01_at24c02_test/at24c02_test.c

@@ -0,0 +1,102 @@
+
+#include <sys/ioctl.h>
+#include <errno.h>
+#include <string.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <linux/i2c.h>
+#include <linux/i2c-dev.h>
+#include <i2c/smbus.h>
+#include "i2cbusses.h"
+#include <time.h>
+
+
+/* ./at24c02 <i2c_bus_number> w "100ask.taobao.com"
+ * ./at24c02 <i2c_bus_number> r
+ */
+
+int main(int argc, char **argv)
+{
+	unsigned char dev_addr = 0x50;
+	unsigned char mem_addr = 0;
+	unsigned char buf[32];
+
+	int file;
+	char filename[20];
+	unsigned char *str;
+
+	int ret;
+
+	struct timespec req;
+	
+	if (argc != 3 && argc != 4)
+	{
+		printf("Usage:\n");
+		printf("write eeprom: %s <i2c_bus_number> w string\n", argv[0]);
+		printf("read  eeprom: %s <i2c_bus_number> r\n", argv[0]);
+		return -1;
+	}
+
+	file = open_i2c_dev(argv[1][0]-'0', filename, sizeof(filename), 0);
+	if (file < 0)
+	{
+		printf("can't open %s\n", filename);
+		return -1;
+	}
+
+	if (set_slave_addr(file, dev_addr, 1))
+	{
+		printf("can't set_slave_addr\n");
+		return -1;
+	}
+
+	if (argv[2][0] == 'w')
+	{
+		// write str: argv[3]
+		str = argv[3];
+
+		req.tv_sec  = 0;
+		req.tv_nsec = 20000000; /* 20ms */
+		
+		while (*str)
+		{
+			// mem_addr, *str
+			// mem_addr++, str++
+			ret = i2c_smbus_write_byte_data(file, mem_addr, *str);
+			if (ret)
+			{
+				printf("i2c_smbus_write_byte_data err\n");
+				return -1;
+			}
+			// wait tWR(10ms)
+			nanosleep(&req, NULL);
+			
+			mem_addr++;
+			str++;
+		}
+		ret = i2c_smbus_write_byte_data(file, mem_addr, 0); // string end char
+		if (ret)
+		{
+			printf("i2c_smbus_write_byte_data err\n");
+			return -1;
+		}
+	}
+	else
+	{
+		// read
+		ret = i2c_smbus_read_i2c_block_data(file, mem_addr, sizeof(buf), buf);
+		if (ret < 0)
+		{
+			printf("i2c_smbus_read_i2c_block_data err\n");
+			return -1;
+		}
+		
+		buf[31] = '\0';
+		printf("get data: %s\n", buf);
+	}
+	
+	return 0;
+	
+}
+

STM32MP157/source/A7/04_I2C/01_at24c02_test/i2cbusses.c

@@ -0,0 +1,455 @@
+/*
+    i2cbusses: Print the installed i2c busses for both 2.4 and 2.6 kernels.
+               Part of user-space programs to access for I2C
+               devices.
+    Copyright (c) 1999-2003  Frodo Looijaard <frodol@dds.nl> and
+                             Mark D. Studebaker <mdsxyz123@yahoo.com>
+    Copyright (C) 2008-2012  Jean Delvare <jdelvare@suse.de>
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program; if not, write to the Free Software
+    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+    MA 02110-1301 USA.
+*/
+
+/* For strdup and snprintf */
+#define _BSD_SOURCE 1 /* for glibc <= 2.19 */
+#define _DEFAULT_SOURCE 1 /* for glibc >= 2.19 */
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/param.h>	/* for NAME_MAX */
+#include <sys/ioctl.h>
+#include <string.h>
+#include <strings.h>	/* for strcasecmp() */
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <limits.h>
+#include <dirent.h>
+#include <fcntl.h>
+#include <errno.h>
+#include "i2cbusses.h"
+#include <linux/i2c.h>
+#include <linux/i2c-dev.h>
+
+enum adt { adt_dummy, adt_isa, adt_i2c, adt_smbus, adt_unknown };
+
+struct adap_type {
+	const char *funcs;
+	const char* algo;
+};
+
+static struct adap_type adap_types[5] = {
+	{ .funcs	= "dummy",
+	  .algo		= "Dummy bus", },
+	{ .funcs	= "isa",
+	  .algo		= "ISA bus", },
+	{ .funcs	= "i2c",
+	  .algo		= "I2C adapter", },
+	{ .funcs	= "smbus",
+	  .algo		= "SMBus adapter", },
+	{ .funcs	= "unknown",
+	  .algo		= "N/A", },
+};
+
+static enum adt i2c_get_funcs(int i2cbus)
+{
+	unsigned long funcs;
+	int file;
+	char filename[20];
+	enum adt ret;
+
+	file = open_i2c_dev(i2cbus, filename, sizeof(filename), 1);
+	if (file < 0)
+		return adt_unknown;
+
+	if (ioctl(file, I2C_FUNCS, &funcs) < 0)
+		ret = adt_unknown;
+	else if (funcs & I2C_FUNC_I2C)
+		ret = adt_i2c;
+	else if (funcs & (I2C_FUNC_SMBUS_BYTE |
+			  I2C_FUNC_SMBUS_BYTE_DATA |
+			  I2C_FUNC_SMBUS_WORD_DATA))
+		ret = adt_smbus;
+	else
+		ret = adt_dummy;
+
+	close(file);
+	return ret;
+}
+
+/* Remove trailing spaces from a string
+   Return the new string length including the trailing NUL */
+static int rtrim(char *s)
+{
+	int i;
+
+	for (i = strlen(s) - 1; i >= 0 && (s[i] == ' ' || s[i] == '\n'); i--)
+		s[i] = '\0';
+	return i + 2;
+}
+
+void free_adapters(struct i2c_adap *adapters)
+{
+	int i;
+
+	for (i = 0; adapters[i].name; i++)
+		free(adapters[i].name);
+	free(adapters);
+}
+
+/* We allocate space for the adapters in bunches. The last item is a
+   terminator, so here we start with room for 7 adapters, which should
+   be enough in most cases. If not, we allocate more later as needed. */
+#define BUNCH	8
+
+/* n must match the size of adapters at calling time */
+static struct i2c_adap *more_adapters(struct i2c_adap *adapters, int n)
+{
+	struct i2c_adap *new_adapters;
+
+	new_adapters = realloc(adapters, (n + BUNCH) * sizeof(struct i2c_adap));
+	if (!new_adapters) {
+		free_adapters(adapters);
+		return NULL;
+	}
+	memset(new_adapters + n, 0, BUNCH * sizeof(struct i2c_adap));
+
+	return new_adapters;
+}
+
+struct i2c_adap *gather_i2c_busses(void)
+{
+	char s[120];
+	struct dirent *de, *dde;
+	DIR *dir, *ddir;
+	FILE *f;
+	char fstype[NAME_MAX], sysfs[NAME_MAX], n[NAME_MAX];
+	int foundsysfs = 0;
+	int len, count = 0;
+	struct i2c_adap *adapters;
+
+	adapters = calloc(BUNCH, sizeof(struct i2c_adap));
+	if (!adapters)
+		return NULL;
+
+	/* look in /proc/bus/i2c */
+	if ((f = fopen("/proc/bus/i2c", "r"))) {
+		while (fgets(s, 120, f)) {
+			char *algo, *name, *type, *all;
+			int len_algo, len_name, len_type;
+			int i2cbus;
+
+			algo = strrchr(s, '\t');
+			*(algo++) = '\0';
+			len_algo = rtrim(algo);
+
+			name = strrchr(s, '\t');
+			*(name++) = '\0';
+			len_name = rtrim(name);
+
+			type = strrchr(s, '\t');
+			*(type++) = '\0';
+			len_type = rtrim(type);
+
+			sscanf(s, "i2c-%d", &i2cbus);
+
+			if ((count + 1) % BUNCH == 0) {
+				/* We need more space */
+				adapters = more_adapters(adapters, count + 1);
+				if (!adapters)
+					return NULL;
+			}
+
+			all = malloc(len_name + len_type + len_algo);
+			if (all == NULL) {
+				free_adapters(adapters);
+				return NULL;
+			}
+			adapters[count].nr = i2cbus;
+			adapters[count].name = strcpy(all, name);
+			adapters[count].funcs = strcpy(all + len_name, type);
+			adapters[count].algo = strcpy(all + len_name + len_type,
+						      algo);
+			count++;
+		}
+		fclose(f);
+		goto done;
+	}
+
+	/* look in sysfs */
+	/* First figure out where sysfs was mounted */
+	if ((f = fopen("/proc/mounts", "r")) == NULL) {
+		goto done;
+	}
+	while (fgets(n, NAME_MAX, f)) {
+		sscanf(n, "%*[^ ] %[^ ] %[^ ] %*s\n", sysfs, fstype);
+		if (strcasecmp(fstype, "sysfs") == 0) {
+			foundsysfs++;
+			break;
+		}
+	}
+	fclose(f);
+	if (! foundsysfs) {
+		goto done;
+	}
+
+	/* Bus numbers in i2c-adapter don't necessarily match those in
+	   i2c-dev and what we really care about are the i2c-dev numbers.
+	   Unfortunately the names are harder to get in i2c-dev */
+	strcat(sysfs, "/class/i2c-dev");
+	if(!(dir = opendir(sysfs)))
+		goto done;
+	/* go through the busses */
+	while ((de = readdir(dir)) != NULL) {
+		if (!strcmp(de->d_name, "."))
+			continue;
+		if (!strcmp(de->d_name, ".."))
+			continue;
+
+		/* this should work for kernels 2.6.5 or higher and */
+		/* is preferred because is unambiguous */
+		len = snprintf(n, NAME_MAX, "%s/%s/name", sysfs, de->d_name);
+		if (len >= NAME_MAX) {
+			fprintf(stderr, "%s: path truncated\n", n);
+			continue;
+		}
+		f = fopen(n, "r");
+		/* this seems to work for ISA */
+		if(f == NULL) {
+			len = snprintf(n, NAME_MAX, "%s/%s/device/name", sysfs,
+				       de->d_name);
+			if (len >= NAME_MAX) {
+				fprintf(stderr, "%s: path truncated\n", n);
+				continue;
+			}
+			f = fopen(n, "r");
+		}
+		/* non-ISA is much harder */
+		/* and this won't find the correct bus name if a driver
+		   has more than one bus */
+		if(f == NULL) {
+			len = snprintf(n, NAME_MAX, "%s/%s/device", sysfs,
+				       de->d_name);
+			if (len >= NAME_MAX) {
+				fprintf(stderr, "%s: path truncated\n", n);
+				continue;
+			}
+			if(!(ddir = opendir(n)))
+				continue;
+			while ((dde = readdir(ddir)) != NULL) {
+				if (!strcmp(dde->d_name, "."))
+					continue;
+				if (!strcmp(dde->d_name, ".."))
+					continue;
+				if ((!strncmp(dde->d_name, "i2c-", 4))) {
+					len = snprintf(n, NAME_MAX,
+						       "%s/%s/device/%s/name",
+						       sysfs, de->d_name,
+						       dde->d_name);
+					if (len >= NAME_MAX) {
+						fprintf(stderr,
+							"%s: path truncated\n",
+							n);
+						continue;
+					}
+					if((f = fopen(n, "r")))
+						goto found;
+				}
+			}
+		}
+
+found:
+		if (f != NULL) {
+			int i2cbus;
+			enum adt type;
+			char *px;
+
+			px = fgets(s, 120, f);
+			fclose(f);
+			if (!px) {
+				fprintf(stderr, "%s: read error\n", n);
+				continue;
+			}
+			if ((px = strchr(s, '\n')) != NULL)
+				*px = 0;
+			if (!sscanf(de->d_name, "i2c-%d", &i2cbus))
+				continue;
+			if (!strncmp(s, "ISA ", 4)) {
+				type = adt_isa;
+			} else {
+				/* Attempt to probe for adapter capabilities */
+				type = i2c_get_funcs(i2cbus);
+			}
+
+			if ((count + 1) % BUNCH == 0) {
+				/* We need more space */
+				adapters = more_adapters(adapters, count + 1);
+				if (!adapters)
+					return NULL;
+			}
+
+			adapters[count].nr = i2cbus;
+			adapters[count].name = strdup(s);
+			if (adapters[count].name == NULL) {
+				free_adapters(adapters);
+				return NULL;
+			}
+			adapters[count].funcs = adap_types[type].funcs;
+			adapters[count].algo = adap_types[type].algo;
+			count++;
+		}
+	}
+	closedir(dir);
+
+done:
+	return adapters;
+}
+
+static int lookup_i2c_bus_by_name(const char *bus_name)
+{
+	struct i2c_adap *adapters;
+	int i, i2cbus = -1;
+
+	adapters = gather_i2c_busses();
+	if (adapters == NULL) {
+		fprintf(stderr, "Error: Out of memory!\n");
+		return -3;
+	}
+
+	/* Walk the list of i2c busses, looking for the one with the
+	   right name */
+	for (i = 0; adapters[i].name; i++) {
+		if (strcmp(adapters[i].name, bus_name) == 0) {
+			if (i2cbus >= 0) {
+				fprintf(stderr,
+					"Error: I2C bus name is not unique!\n");
+				i2cbus = -4;
+				goto done;
+			}
+			i2cbus = adapters[i].nr;
+		}
+	}
+
+	if (i2cbus == -1)
+		fprintf(stderr, "Error: I2C bus name doesn't match any "
+			"bus present!\n");
+
+done:
+	free_adapters(adapters);
+	return i2cbus;
+}
+
+/*
+ * Parse an I2CBUS command line argument and return the corresponding
+ * bus number, or a negative value if the bus is invalid.
+ */
+int lookup_i2c_bus(const char *i2cbus_arg)
+{
+	unsigned long i2cbus;
+	char *end;
+
+	i2cbus = strtoul(i2cbus_arg, &end, 0);
+	if (*end || !*i2cbus_arg) {
+		/* Not a number, maybe a name? */
+		return lookup_i2c_bus_by_name(i2cbus_arg);
+	}
+	if (i2cbus > 0xFFFFF) {
+		fprintf(stderr, "Error: I2C bus out of range!\n");
+		return -2;
+	}
+
+	return i2cbus;
+}
+
+/*
+ * Parse a CHIP-ADDRESS command line argument and return the corresponding
+ * chip address, or a negative value if the address is invalid.
+ */
+int parse_i2c_address(const char *address_arg, int all_addrs)
+{
+	long address;
+	char *end;
+	long min_addr = 0x08;
+	long max_addr = 0x77;
+
+	address = strtol(address_arg, &end, 0);
+	if (*end || !*address_arg) {
+		fprintf(stderr, "Error: Chip address is not a number!\n");
+		return -1;
+	}
+
+	if (all_addrs) {
+		min_addr = 0x00;
+		max_addr = 0x7f;
+	}
+
+	if (address < min_addr || address > max_addr) {
+		fprintf(stderr, "Error: Chip address out of range "
+			"(0x%02lx-0x%02lx)!\n", min_addr, max_addr);
+		return -2;
+	}
+
+	return address;
+}
+
+int open_i2c_dev(int i2cbus, char *filename, size_t size, int quiet)
+{
+	int file, len;
+
+	len = snprintf(filename, size, "/dev/i2c/%d", i2cbus);
+	if (len >= (int)size) {
+		fprintf(stderr, "%s: path truncated\n", filename);
+		return -EOVERFLOW;
+	}
+	file = open(filename, O_RDWR);
+
+	if (file < 0 && (errno == ENOENT || errno == ENOTDIR)) {
+		len = snprintf(filename, size, "/dev/i2c-%d", i2cbus);
+		if (len >= (int)size) {
+			fprintf(stderr, "%s: path truncated\n", filename);
+			return -EOVERFLOW;
+		}
+		file = open(filename, O_RDWR);
+	}
+
+	if (file < 0 && !quiet) {
+		if (errno == ENOENT) {
+			fprintf(stderr, "Error: Could not open file "
+				"`/dev/i2c-%d' or `/dev/i2c/%d': %s\n",
+				i2cbus, i2cbus, strerror(ENOENT));
+		} else {
+			fprintf(stderr, "Error: Could not open file "
+				"`%s': %s\n", filename, strerror(errno));
+			if (errno == EACCES)
+				fprintf(stderr, "Run as root?\n");
+		}
+	}
+
+	return file;
+}
+
+int set_slave_addr(int file, int address, int force)
+{
+	/* With force, let the user read from/write to the registers
+	   even when a driver is also running */
+	if (ioctl(file, force ? I2C_SLAVE_FORCE : I2C_SLAVE, address) < 0) {
+		fprintf(stderr,
+			"Error: Could not set address to 0x%02x: %s\n",
+			address, strerror(errno));
+		return -errno;
+	}
+
+	return 0;
+}

STM32MP157/source/A7/04_I2C/01_at24c02_test/i2cbusses.h

@@ -0,0 +1,44 @@
+/*
+    i2cbusses.h - Part of the i2c-tools package
+
+    Copyright (C) 2004-2010  Jean Delvare <jdelvare@suse.de>
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program; if not, write to the Free Software
+    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+    MA 02110-1301 USA.
+*/
+
+#ifndef _I2CBUSSES_H
+#define _I2CBUSSES_H
+
+#include <unistd.h>
+
+struct i2c_adap {
+	int nr;
+	char *name;
+	const char *funcs;
+	const char *algo;
+};
+
+struct i2c_adap *gather_i2c_busses(void);
+void free_adapters(struct i2c_adap *adapters);
+
+int lookup_i2c_bus(const char *i2cbus_arg);
+int parse_i2c_address(const char *address_arg, int all_addrs);
+int open_i2c_dev(int i2cbus, char *filename, size_t size, int quiet);
+int set_slave_addr(int file, int address, int force);
+
+#define MISSING_FUNC_FMT	"Error: Adapter does not have %s capability\n"
+
+#endif

STM32MP157/source/A7/04_I2C/01_at24c02_test/include/i2c/smbus.h

@@ -0,0 +1,52 @@
+/*
+    smbus.h - SMBus level access helper functions
+
+    Copyright (C) 1995-1997  Simon G. Vogl
+    Copyright (C) 1998-1999  Frodo Looijaard <frodol@dds.nl>
+    Copyright (C) 2012-2017  Jean Delvare <jdelvare@suse.de>
+
+    This library is free software; you can redistribute it and/or modify
+    it under the terms of the GNU Lesser General Public License as published
+    by the Free Software Foundation; either version 2.1 of the License, or
+    (at your option) any later version.
+*/
+
+#ifndef LIB_I2C_SMBUS_H
+#define LIB_I2C_SMBUS_H
+
+#define I2C_API_VERSION		0x100
+
+#include <linux/types.h>
+#include <linux/i2c.h>
+
+extern __s32 i2c_smbus_access(int file, char read_write, __u8 command,
+			      int size, union i2c_smbus_data *data);
+
+extern __s32 i2c_smbus_write_quick(int file, __u8 value);
+extern __s32 i2c_smbus_read_byte(int file);
+extern __s32 i2c_smbus_write_byte(int file, __u8 value);
+extern __s32 i2c_smbus_read_byte_data(int file, __u8 command);
+extern __s32 i2c_smbus_write_byte_data(int file, __u8 command, __u8 value);
+extern __s32 i2c_smbus_read_word_data(int file, __u8 command);
+extern __s32 i2c_smbus_write_word_data(int file, __u8 command, __u16 value);
+extern __s32 i2c_smbus_process_call(int file, __u8 command, __u16 value);
+
+/* Returns the number of read bytes */
+extern __s32 i2c_smbus_read_block_data(int file, __u8 command, __u8 *values);
+extern __s32 i2c_smbus_write_block_data(int file, __u8 command, __u8 length,
+					const __u8 *values);
+
+/* Returns the number of read bytes */
+/* Until kernel 2.6.22, the length is hardcoded to 32 bytes. If you
+   ask for less than 32 bytes, your code will only work with kernels
+   2.6.23 and later. */
+extern __s32 i2c_smbus_read_i2c_block_data(int file, __u8 command, __u8 length,
+					   __u8 *values);
+extern __s32 i2c_smbus_write_i2c_block_data(int file, __u8 command, __u8 length,
+					    const __u8 *values);
+
+/* Returns the number of read bytes */
+extern __s32 i2c_smbus_block_process_call(int file, __u8 command, __u8 length,
+					  __u8 *values);
+
+#endif /* LIB_I2C_SMBUS_H */

STM32MP157/source/A7/04_I2C/01_at24c02_test/smbus.c

@@ -0,0 +1,214 @@
+/*
+    smbus.c - SMBus level access helper functions
+
+    Copyright (C) 1995-1997  Simon G. Vogl
+    Copyright (C) 1998-1999  Frodo Looijaard <frodol@dds.nl>
+    Copyright (C) 2012-2013  Jean Delvare <jdelvare@suse.de>
+
+    This library is free software; you can redistribute it and/or modify
+    it under the terms of the GNU Lesser General Public License as published
+    by the Free Software Foundation; either version 2.1 of the License, or
+    (at your option) any later version.
+*/
+
+#include <errno.h>
+#include <stddef.h>
+#include <i2c/smbus.h>
+#include <sys/ioctl.h>
+#include <linux/types.h>
+#include <linux/i2c.h>
+#include <linux/i2c-dev.h>
+
+/* Compatibility defines */
+#ifndef I2C_SMBUS_I2C_BLOCK_BROKEN
+#define I2C_SMBUS_I2C_BLOCK_BROKEN I2C_SMBUS_I2C_BLOCK_DATA
+#endif
+#ifndef I2C_FUNC_SMBUS_PEC
+#define I2C_FUNC_SMBUS_PEC I2C_FUNC_SMBUS_HWPEC_CALC
+#endif
+
+__s32 i2c_smbus_access(int file, char read_write, __u8 command,
+		       int size, union i2c_smbus_data *data)
+{
+	struct i2c_smbus_ioctl_data args;
+	__s32 err;
+
+	args.read_write = read_write;
+	args.command = command;
+	args.size = size;
+	args.data = data;
+
+	err = ioctl(file, I2C_SMBUS, &args);
+	if (err == -1)
+		err = -errno;
+	return err;
+}
+
+
+__s32 i2c_smbus_write_quick(int file, __u8 value)
+{
+	return i2c_smbus_access(file, value, 0, I2C_SMBUS_QUICK, NULL);
+}
+
+__s32 i2c_smbus_read_byte(int file)
+{
+	union i2c_smbus_data data;
+	int err;
+
+	err = i2c_smbus_access(file, I2C_SMBUS_READ, 0, I2C_SMBUS_BYTE, &data);
+	if (err < 0)
+		return err;
+
+	return 0x0FF & data.byte;
+}
+
+__s32 i2c_smbus_write_byte(int file, __u8 value)
+{
+	return i2c_smbus_access(file, I2C_SMBUS_WRITE, value,
+				I2C_SMBUS_BYTE, NULL);
+}
+
+__s32 i2c_smbus_read_byte_data(int file, __u8 command)
+{
+	union i2c_smbus_data data;
+	int err;
+
+	err = i2c_smbus_access(file, I2C_SMBUS_READ, command,
+			       I2C_SMBUS_BYTE_DATA, &data);
+	if (err < 0)
+		return err;
+
+	return 0x0FF & data.byte;
+}
+
+__s32 i2c_smbus_write_byte_data(int file, __u8 command, __u8 value)
+{
+	union i2c_smbus_data data;
+	data.byte = value;
+	return i2c_smbus_access(file, I2C_SMBUS_WRITE, command,
+				I2C_SMBUS_BYTE_DATA, &data);
+}
+
+__s32 i2c_smbus_read_word_data(int file, __u8 command)
+{
+	union i2c_smbus_data data;
+	int err;
+
+	err = i2c_smbus_access(file, I2C_SMBUS_READ, command,
+			       I2C_SMBUS_WORD_DATA, &data);
+	if (err < 0)
+		return err;
+
+	return 0x0FFFF & data.word;
+}
+
+__s32 i2c_smbus_write_word_data(int file, __u8 command, __u16 value)
+{
+	union i2c_smbus_data data;
+	data.word = value;
+	return i2c_smbus_access(file, I2C_SMBUS_WRITE, command,
+				I2C_SMBUS_WORD_DATA, &data);
+}
+
+__s32 i2c_smbus_process_call(int file, __u8 command, __u16 value)
+{
+	union i2c_smbus_data data;
+	data.word = value;
+	if (i2c_smbus_access(file, I2C_SMBUS_WRITE, command,
+			     I2C_SMBUS_PROC_CALL, &data))
+		return -1;
+	else
+		return 0x0FFFF & data.word;
+}
+
+/* Returns the number of read bytes */
+__s32 i2c_smbus_read_block_data(int file, __u8 command, __u8 *values)
+{
+	union i2c_smbus_data data;
+	int i, err;
+
+	err = i2c_smbus_access(file, I2C_SMBUS_READ, command,
+			       I2C_SMBUS_BLOCK_DATA, &data);
+	if (err < 0)
+		return err;
+
+	for (i = 1; i <= data.block[0]; i++)
+		values[i-1] = data.block[i];
+	return data.block[0];
+}
+
+__s32 i2c_smbus_write_block_data(int file, __u8 command, __u8 length,
+				 const __u8 *values)
+{
+	union i2c_smbus_data data;
+	int i;
+	if (length > I2C_SMBUS_BLOCK_MAX)
+		length = I2C_SMBUS_BLOCK_MAX;
+	for (i = 1; i <= length; i++)
+		data.block[i] = values[i-1];
+	data.block[0] = length;
+	return i2c_smbus_access(file, I2C_SMBUS_WRITE, command,
+				I2C_SMBUS_BLOCK_DATA, &data);
+}
+
+/* Returns the number of read bytes */
+/* Until kernel 2.6.22, the length is hardcoded to 32 bytes. If you
+   ask for less than 32 bytes, your code will only work with kernels
+   2.6.23 and later. */
+__s32 i2c_smbus_read_i2c_block_data(int file, __u8 command, __u8 length,
+				    __u8 *values)
+{
+	union i2c_smbus_data data;
+	int i, err;
+
+	if (length > I2C_SMBUS_BLOCK_MAX)
+		length = I2C_SMBUS_BLOCK_MAX;
+	data.block[0] = length;
+
+	err = i2c_smbus_access(file, I2C_SMBUS_READ, command,
+			       length == 32 ? I2C_SMBUS_I2C_BLOCK_BROKEN :
+				I2C_SMBUS_I2C_BLOCK_DATA, &data);
+	if (err < 0)
+		return err;
+
+	for (i = 1; i <= data.block[0]; i++)
+		values[i-1] = data.block[i];
+	return data.block[0];
+}
+
+__s32 i2c_smbus_write_i2c_block_data(int file, __u8 command, __u8 length,
+				     const __u8 *values)
+{
+	union i2c_smbus_data data;
+	int i;
+	if (length > I2C_SMBUS_BLOCK_MAX)
+		length = I2C_SMBUS_BLOCK_MAX;
+	for (i = 1; i <= length; i++)
+		data.block[i] = values[i-1];
+	data.block[0] = length;
+	return i2c_smbus_access(file, I2C_SMBUS_WRITE, command,
+				I2C_SMBUS_I2C_BLOCK_BROKEN, &data);
+}
+
+/* Returns the number of read bytes */
+__s32 i2c_smbus_block_process_call(int file, __u8 command, __u8 length,
+				   __u8 *values)
+{
+	union i2c_smbus_data data;
+	int i, err;
+
+	if (length > I2C_SMBUS_BLOCK_MAX)
+		length = I2C_SMBUS_BLOCK_MAX;
+	for (i = 1; i <= length; i++)
+		data.block[i] = values[i-1];
+	data.block[0] = length;
+
+	err = i2c_smbus_access(file, I2C_SMBUS_WRITE, command,
+			       I2C_SMBUS_BLOCK_PROC_CALL, &data);
+	if (err < 0)
+		return err;
+
+	for (i = 1; i <= data.block[0]; i++)
+		values[i-1] = data.block[i];
+	return data.block[0];
+}