Re: [PATCH v2 1/3] i2c: Add parameters to sysfs-added i2c devices

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On 5/10/2016 10:11 AM, minyard@xxxxxxx wrote:
From: Corey Minyard <cminyard@xxxxxxxxxx>

Some devices might need parameters to control their operation,
add the ability to pass these parameters to the client.

This also makes the parsing of sysfs-added I2C devices a little
more flexible, allowing tabs and arbitrary numbers of spaces.

Signed-off-by: Corey Minyard <cminyard@xxxxxxxxxx>
Tested on QDF2432 with I2C IPMI client to ensure no regressions are introduced.
Tested-by: Naveen Kaje <nkaje@xxxxxxxxxxxxxx>

---
  drivers/i2c/i2c-core.c | 43 +++++++++++++++++++++++++++++++------------
  include/linux/i2c.h    |  3 +++
  2 files changed, 34 insertions(+), 12 deletions(-)

diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index e584d88..069c385 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -51,6 +51,7 @@
  #include <linux/pm_domain.h>
  #include <linux/pm_runtime.h>
  #include <linux/pm_wakeirq.h>
+#include <linux/ctype.h>
  #include <linux/property.h>
  #include <linux/rwsem.h>
  #include <linux/slab.h>
@@ -780,7 +781,10 @@ static void i2c_device_shutdown(struct device *dev)
static void i2c_client_dev_release(struct device *dev)
  {
-	kfree(to_i2c_client(dev));
+	struct i2c_client *client = to_i2c_client(dev);
+
+	kfree(client->parms);
+	kfree(client);
  }
static ssize_t
@@ -1047,6 +1051,13 @@ i2c_new_device(struct i2c_adapter *adap, struct i2c_board_info const *info)
  	client->flags = info->flags;
  	client->addr = info->addr;
  	client->irq = info->irq;
+	if (info->parms) {
+		client->parms = kstrdup(info->parms, GFP_KERNEL);
+		if (!client->parms) {
+			dev_err(&adap->dev, "Out of memory allocating parms\n");
+			goto out_err_silent;
+		}
+	}
strlcpy(client->name, info->type, sizeof(client->name)); @@ -1196,31 +1207,39 @@ i2c_sysfs_new_device(struct device *dev, struct device_attribute *attr,
  	struct i2c_adapter *adap = to_i2c_adapter(dev);
  	struct i2c_board_info info;
  	struct i2c_client *client;
-	char *blank, end;
+	char *pos, end;
  	int res;
memset(&info, 0, sizeof(struct i2c_board_info)); - blank = strchr(buf, ' ');
-	if (!blank) {
+	pos = strpbrk(buf, " \t");
+	if (!pos) {
  		dev_err(dev, "%s: Missing parameters\n", "new_device");
  		return -EINVAL;
  	}
-	if (blank - buf > I2C_NAME_SIZE - 1) {
+	if (pos - buf > I2C_NAME_SIZE - 1) {
  		dev_err(dev, "%s: Invalid device name\n", "new_device");
  		return -EINVAL;
  	}
-	memcpy(info.type, buf, blank - buf);
+	memcpy(info.type, buf, pos - buf);
- /* Parse remaining parameters, reject extra parameters */
-	res = sscanf(++blank, "%hi%c", &info.addr, &end);
-	if (res < 1) {
+	while (isspace(*pos))
+		pos++;
+
+	/* Parse address, saving remaining parameters. */
+	res = sscanf(pos, "%hi%c", &info.addr, &end);
+	if (res < 1 || (res > 1 && !isspace(end))) {
  		dev_err(dev, "%s: Can't parse I2C address\n", "new_device");
  		return -EINVAL;
  	}
-	if (res > 1  && end != '\n') {
-		dev_err(dev, "%s: Extra parameters\n", "new_device");
-		return -EINVAL;
+	if (res > 1) {
+		/* Extra parms, skip the address and space. */
+		while (!isspace(*pos))
+			pos++;
+		while (isspace(*pos))
+			pos++;
+		if (*pos)
+			info.parms = pos;
  	}
if ((info.addr & I2C_ADDR_OFFSET_TEN_BIT) == I2C_ADDR_OFFSET_TEN_BIT) {
diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index 200cf13b..35db0dd 100644
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -225,6 +225,7 @@ struct i2c_client {
  	char name[I2C_NAME_SIZE];
  	struct i2c_adapter *adapter;	/* the adapter we sit on	*/
  	struct device dev;		/* the device structure		*/
+	char *parms;			/* sysfs extra parms		*/
  	int irq;			/* irq issued by device		*/
  	struct list_head detected;
  #if IS_ENABLED(CONFIG_I2C_SLAVE)
@@ -282,6 +283,7 @@ static inline int i2c_slave_event(struct i2c_client *client,
   * @archdata: copied into i2c_client.dev.archdata
   * @of_node: pointer to OpenFirmware device node
   * @fwnode: device node supplied by the platform firmware
+ * @parms: Parameters supplied on the sysfs command line
   * @irq: stored in i2c_client.irq
   *
   * I2C doesn't actually support hardware probing, although controllers and
@@ -303,6 +305,7 @@ struct i2c_board_info {
  	struct dev_archdata	*archdata;
  	struct device_node *of_node;
  	struct fwnode_handle *fwnode;
+	char            *parms;
  	int		irq;
  };

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