Re: [RFC] [PATCH] misc : ROHM BH1780GLI Ambient light sensor Driver
From: Hemanth V
Date: Fri May 21 2010 - 08:40:21 EST
----- Original Message -----
From: "Daniel Mack" <daniel@xxxxxxxx>
To: "Hemanth V" <hemanthv@xxxxxx>
Cc: <linux-kernel@xxxxxxxxxxxxxxx>; <linux-omap@xxxxxxxxxxxxxxx>;
<linux-input@xxxxxxxxxxxxxxx>
Sent: Friday, May 21, 2010 5:33 PM
Subject: Re: [RFC] [PATCH] misc : ROHM BH1780GLI Ambient light sensor Driver
Hi,
On Fri, May 21, 2010 at 05:05:50PM +0530, Hemanth V wrote:
Corrected the mailing list, should be linux-kernel
This patch adds support for ROHM BH1780GLI Ambient light sensor.
BH1780 supports I2C interface. Driver supports read/update of power state
and
read of lux value (through SYSFS). Writing value 3 to power_state enables
the
sensor and current lux value could be read.
FWIW, this looks pretty good to me, just some minor things below.
Thanks for the review comment, responses inline
Daniel
Signed-off-by: Hemanth V <hemanthv@xxxxxx>
---
drivers/misc/Kconfig | 11 ++
drivers/misc/Makefile | 1 +
drivers/misc/bh1780gli.c | 278
++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 290 insertions(+), 0 deletions(-)
create mode 100644 drivers/misc/bh1780gli.c
diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
index 0d0d625..0687a0c 100644
--- a/drivers/misc/Kconfig
+++ b/drivers/misc/Kconfig
@@ -278,6 +278,17 @@ config SENSORS_TSL2550
This driver can also be built as a module. If so, the module
will be called tsl2550.
+config SENSORS_BH1780
+ tristate "ROHM BH1780GLI ambient light sensor"
+ depends on I2C && SYSFS
+ help
+ If you say yes here you get support for the ROHM BH1780GLI
+ ambient light sensor.
+
+ This driver can also be built as a module. If so, the module
+ will be called bh1780gli.
+
+
config EP93XX_PWM
tristate "EP93xx PWM support"
depends on ARCH_EP93XX
diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
index 7b6f7ee..c479d91 100644
--- a/drivers/misc/Makefile
+++ b/drivers/misc/Makefile
@@ -30,3 +30,4 @@ obj-$(CONFIG_IWMC3200TOP) += iwmc3200top/
obj-y += eeprom/
obj-y += cb710/
obj-$(CONFIG_VMWARE_BALLOON) += vmware_balloon.o
+obj-$(CONFIG_SENSORS_BH1780) += bh1780gli.o
diff --git a/drivers/misc/bh1780gli.c b/drivers/misc/bh1780gli.c
new file mode 100644
index 0000000..9b4137d
--- /dev/null
+++ b/drivers/misc/bh1780gli.c
@@ -0,0 +1,278 @@
+/*
+ * bh1780gli.c
+ * ROHM Ambient Light Sensor Driver
+ *
+ * Copyright (C) 2010 Texas Instruments
+ * Author: Hemanth V <hemanthv@xxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
it
+ * under the terms of the GNU General Public License version 2 as
published by
+ * the Free Software Foundation.
+ *
+ * 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, see <http://www.gnu.org/licenses/>.
+ */
+#include <linux/i2c.h>
+#include <linux/slab.h>
+#include <linux/mutex.h>
+#include <linux/platform_device.h>
+#include <linux/delay.h>
+
+#define BH1780_REG_CONTROL 0x80
+#define BH1780_REG_PARTID 0x8A
+#define BH1780_REG_MANFID 0x8B
+#define BH1780_REG_DLOW 0x8C
+#define BH1780_REG_DHIGH 0x8D
+
+#define BH1780_REVMASK (0xf)
+#define BH1780_POWMASK (0x3)
+#define BH1780_POFF (0x0)
+#define BH1780_PON (0x3)
Just a nit ... something's wrong with the indentation here.
Will fix
+/* power on settling time in ms */
+#define BH1780_PON_DELAY 2
+
+struct bh1780_data {
+ struct i2c_client *client;
+ int power_state;
+ /* lock for sysfs operations */
+ struct mutex lock;
+};
+
+int bh1780_write(struct bh1780_data *ddata, u8 reg, u8 val, char *msg)
Should be static.
Yes, agreed
+{
+ int ret = i2c_smbus_write_byte_data(ddata->client, reg, val);
+ if (ret < 0)
+ dev_err(&ddata->client->dev,
+ "i2c_smbus_write_byte_data failed error %d\
+ Register (%s)\n", ret, msg);
+ return ret;
+}
+
+int bh1780_read(struct bh1780_data *ddata, u8 reg, char *msg)
Dito.
Yes, agreed
+{
+ int ret = i2c_smbus_read_byte_data(ddata->client, reg);
+ if (ret < 0)
+ dev_err(&ddata->client->dev,
+ "i2c_smbus_read_byte_data failed error %d\
+ Register (%s)\n", ret, msg);
+ return ret;
+}
+
+static ssize_t bh1780_show_lux(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+
+ struct platform_device *pdev = to_platform_device(dev);
+ struct bh1780_data *ddata = platform_get_drvdata(pdev);
+ int lsb, msb;
+
+ lsb = bh1780_read(ddata, BH1780_REG_DLOW, "DLOW");
+ if (lsb < 0)
+ return lsb;
+
+ msb = bh1780_read(ddata, BH1780_REG_DHIGH, "DHIGH");
+ if (msb < 0)
+ return msb;
+
+ return sprintf(buf, "%d\n", (msb << 8) | lsb);
+}
+
+static ssize_t bh1780_show_power_state(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ struct platform_device *pdev = to_platform_device(dev);
+ struct bh1780_data *ddata = platform_get_drvdata(pdev);
+ int state;
+
+ state = bh1780_read(ddata, BH1780_REG_CONTROL, "CONTROL");
+ if (state < 0)
+ return state;
+
+ return sprintf(buf, "%d\n", state & BH1780_POWMASK);
+}
+
+static ssize_t bh1780_store_power_state(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct platform_device *pdev = to_platform_device(dev);
+ struct bh1780_data *ddata = platform_get_drvdata(pdev);
+ unsigned long val;
+ int error;
+
+ error = strict_strtoul(buf, 0, &val);
+ if (error)
+ return error;
+
+ if (val < BH1780_POFF || val > BH1780_PON)
+ return -EINVAL;
+
+ mutex_lock(&ddata->lock);
+
+ error = bh1780_write(ddata, BH1780_REG_CONTROL, val, "CONTROL");
+ if (error < 0) {
+ mutex_unlock(&ddata->lock);
+ return error;
+ }
+
+ msleep(BH1780_PON_DELAY);
Hmm, what do you wait for here?
Settling time delay required before lux read out
+ ddata->power_state = val;
+ mutex_unlock(&ddata->lock);
And I don't get the usage of the mutex here. Can you explain?
Basically prevent two concurrent sysfs calls from interfering
with each other
+ return count;
+
+}
Remove the empty line. Or move it above the return statement.
Yes, agreed
+
+static DEVICE_ATTR(lux, S_IRUGO, bh1780_show_lux, NULL);
+
+static DEVICE_ATTR(power_state, S_IWUSR | S_IRUGO,
+ bh1780_show_power_state, bh1780_store_power_state);
+
+static struct attribute *bh1780_attributes[] = {
+ &dev_attr_power_state.attr,
+ &dev_attr_lux.attr,
+ NULL
+};
+
+static const struct attribute_group bh1780_attr_group = {
+ .attrs = bh1780_attributes,
+};
+
+static int __devinit bh1780_probe(struct i2c_client *client,
+ const struct i2c_device_id *id)
+{
+ int ret;
+ struct bh1780_data *ddata = NULL;
The initialization isn't needed.
This is basically added for the first goto error, to prevent
any garbage values
+ struct i2c_adapter *adapter = to_i2c_adapter(client->dev.parent);
+
+ if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE)) {
+ ret = -EIO;
+ goto err_op_failed;
+ }
+
+ ddata = kzalloc(sizeof(struct bh1780_data), GFP_KERNEL);
+ if (ddata == NULL) {
+ ret = -ENOMEM;
+ goto err_op_failed;
+ }
+
+ ddata->client = client;
+ i2c_set_clientdata(client, ddata);
+
+ ret = bh1780_read(ddata, BH1780_REG_PARTID, "PART ID");
+ if (ret < 0)
+ goto err_op_failed;
+
+ dev_info(&client->dev, "Ambient Light Sensor, Rev : %d\n",
+ (ret & BH1780_REVMASK));
+
+ mutex_init(&ddata->lock);
+
+ ret = sysfs_create_group(&client->dev.kobj, &bh1780_attr_group);
+ if (ret)
+ goto err_op_failed;
+
+ return 0;
+
+err_op_failed:
+ if (ddata != NULL)
+ kfree(ddata);
kfree() is resitant against NULL pointers, so you can call it
unconditionally.
Yes, agreed
+
+ return ret;
+}
+
+static int __devexit bh1780_remove(struct i2c_client *client)
+{
+ struct bh1780_data *ddata;
+
+ ddata = i2c_get_clientdata(client);
+ sysfs_remove_group(&client->dev.kobj, &bh1780_attr_group);
+
+ if (ddata != NULL) {
+ i2c_set_clientdata(client, NULL);
+ kfree(ddata);
+ }
Same here.
Yes, agreed
+
+ return 0;
+}
+
+#ifdef CONFIG_PM
+static int bh1780_suspend(struct i2c_client *client, pm_message_t mesg)
+{
+ struct bh1780_data *ddata;
+ int state, ret;
+
+ ddata = i2c_get_clientdata(client);
+ state = bh1780_read(ddata, BH1780_REG_CONTROL, "CONTROL");
+ if (state < 0)
+ return state;
+
+ ddata->power_state = state & BH1780_POWMASK;
+
+ ret = bh1780_write(ddata, BH1780_REG_CONTROL, BH1780_POFF,
+ "CONTROL");
+
+ if (ret < 0)
+ return ret;
+
+ return 0;
+}
+
+static int bh1780_resume(struct i2c_client *client)
+{
+ struct bh1780_data *ddata;
+ int state, ret;
+
+ ddata = i2c_get_clientdata(client);
+ state = ddata->power_state;
+
+ ret = bh1780_write(ddata, BH1780_REG_CONTROL, state,
+ "CONTROL");
+
+ if (ret < 0)
+ return ret;
+
+ return 0;
+}
#else
static inline int bh1780_suspend(struct i2c_client *client, pm_message_t
mesg) {}
static inline int bh1780_resume(struct i2c_client *client) {}
Yes, I could add as below which seems to be used in quite a few
misc drivers
#define bh1780_suspend NULL
+#endif
+
+static const struct i2c_device_id bh1780_id[] = {
+ { "bh1780", 0 },
+ { },
+};
+
+static struct i2c_driver bh1780_driver = {
+ .probe = bh1780_probe,
+ .remove = bh1780_remove,
+ .id_table = bh1780_id,
+#ifdef CONFIG_PM
... then this #ifdef can go away.
+ .suspend = bh1780_suspend,
+ .resume = bh1780_resume,
+#endif
+ .driver = {
+ .name = "bh1780"
+ },
+};
+
+static int __init bh1780_init(void)
+{
+ return i2c_add_driver(&bh1780_driver);
+}
+
+static void __exit bh1780_exit(void)
+{
+ i2c_del_driver(&bh1780_driver);
+}
+
+module_init(bh1780_init)
+module_exit(bh1780_exit)
+
+MODULE_DESCRIPTION("BH1780GLI Ambient Light Sensor Driver");
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Hemanth V <hemanthv@xxxxxx>");
--
1.5.6.3
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