Date:	Thu, 10 Nov 2011 18:22:32 +0000
From:	Jonathan Cameron <jic23@...nel.org>
To:	oskar.andero@...yericsson.com
CC:	dmitry.torokhov@...il.com, linux-input@...r.kernel.org,
	linux-kernel@...r.kernel.org, aghayal@...eaurora.org,
	Courtney Cavin <courtney.cavin@...yericsson.com>
Subject: Re: [PATCH] input: add driver support for Sharp gp2ap002a00f proximity
 sensor

On 11/10/2011 04:07 PM, oskar.andero@...yericsson.com wrote:
> From: Courtney Cavin <courtney.cavin@...yericsson.com>
ALS sensor in input?  Please see all the previous discussions about
this.  I'm guessing you are aware of this given you cc'd me though!

Having read driver, this is a proximity switch. Basically it's a button.
The interface used should reflect this rather than pretending you are
outputing an ABS value.  Hence this one probably does fit squarely in
input, but that's for Dmitry to comment on.

Also, irq fields contain irqs not gpios + the two gpio related pdata
functions need justification.

Various small points inline.

> 
> Signed-off-by: Courtney Cavin <courtney.cavin@...yericsson.com>
> Signed-off-by: Oskar Andero <oskar.andero@...yericsson.com>
> ---
>  drivers/input/misc/Kconfig        |   11 ++
>  drivers/input/misc/Makefile       |    1 +
>  drivers/input/misc/gp2ap002a00f.c |  265 +++++++++++++++++++++++++++++++++++++
>  include/linux/gp2ap002a00f.h      |   13 ++
>  4 files changed, 290 insertions(+), 0 deletions(-)
>  create mode 100644 drivers/input/misc/gp2ap002a00f.c
>  create mode 100644 include/linux/gp2ap002a00f.h
> 
> diff --git a/drivers/input/misc/Kconfig b/drivers/input/misc/Kconfig
> index 22d875f..dee96a0 100644
> --- a/drivers/input/misc/Kconfig
> +++ b/drivers/input/misc/Kconfig
> @@ -544,4 +544,15 @@ config INPUT_XEN_KBDDEV_FRONTEND
>  	  To compile this driver as a module, choose M here: the
>  	  module will be called xen-kbdfront.
>  
> +config INPUT_GP2A
> +	tristate "Sharp GP2AP002A00F I2C Proximity/Opto sensor driver"
> +	depends on I2C
> +	default n
> +	help
> +	  Say Y here if you have a Sharp GP2AP002A00F proximity/als combo-chip
> +	  hooked to an I2C bus.
> +
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called gp2ap002a00f.
> +
>  endif
> diff --git a/drivers/input/misc/Makefile b/drivers/input/misc/Makefile
> index a244fc6..1681993 100644
> --- a/drivers/input/misc/Makefile
> +++ b/drivers/input/misc/Makefile
> @@ -22,6 +22,7 @@ obj-$(CONFIG_INPUT_CMA3000)		+= cma3000_d0x.o
>  obj-$(CONFIG_INPUT_CMA3000_I2C)		+= cma3000_d0x_i2c.o
>  obj-$(CONFIG_INPUT_COBALT_BTNS)		+= cobalt_btns.o
>  obj-$(CONFIG_INPUT_DM355EVM)		+= dm355evm_keys.o
> +obj-$(CONFIG_INPUT_GP2A)		+= gp2ap002a00f.o
>  obj-$(CONFIG_HP_SDC_RTC)		+= hp_sdc_rtc.o
>  obj-$(CONFIG_INPUT_IXP4XX_BEEPER)	+= ixp4xx-beeper.o
>  obj-$(CONFIG_INPUT_KEYSPAN_REMOTE)	+= keyspan_remote.o
> diff --git a/drivers/input/misc/gp2ap002a00f.c b/drivers/input/misc/gp2ap002a00f.c
> new file mode 100644
> index 0000000..b1af83a
> --- /dev/null
> +++ b/drivers/input/misc/gp2ap002a00f.c
> @@ -0,0 +1,265 @@
> +/*
> + * Copyright (C) 2009,2010 Sony Ericsson Mobile Communications Inc.
> + *
> + * Author: Courtney Cavin <courtney.cavin@...yericsson.com>
> + * Prepared for up-stream by: Oskar Andero <oskar.andero@...yericsson.com>
> + *
> + * 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.
> + */
> +
> +#include <linux/i2c.h>
> +#include <linux/irq.h>
> +#include <linux/slab.h>
> +#include <linux/input.h>
> +#include <linux/module.h>
> +#include <linux/workqueue.h>
> +#include <linux/interrupt.h>
> +#include <linux/gpio.h>
> +#include <linux/delay.h>
That looks like a bold location for the header.
Surely a sub directory?
> +#include <linux/gp2ap002a00f.h>
> +
> +struct gp2a_data {
> +	struct input_dev *device;
> +	struct gp2a_platform_data *pdata;
> +	struct i2c_client *i2c_client;
> +};
> +
> +enum gp2a_addr {
> +	GP2A_ADDR_PROX	= 0x0,
> +	GP2A_ADDR_GAIN	= 0x1,
> +	GP2A_ADDR_HYS	= 0x2,
> +	GP2A_ADDR_CYCLE	= 0x3,
> +	GP2A_ADDR_OPMOD	= 0x4,
> +	GP2A_ADDR_CON	= 0x6
> +};
> +
> +enum gp2a_controls {
> +	GP2A_CTRL_SSD	= 0x01
> +};
> +
> +#define NUM_TRIES 5
> +static int gp2a_write_byte(struct gp2a_data *dt, u8 reg, u8 val)
> +{
> +	int error;
> +	int n;
> +	struct device *dev = &dt->i2c_client->dev;
> +
Usual question here is whether you every actually get errors?  If you do
then
something fishy is going on.  By all means check for them, but putting this
repeated try logic into the driver doesn't normally make any sense.  It just
complicates the driver code to deal with a very rare condition.
Without that, this becomes a pointless wrapper and so should be replaced
inline within the code with direct calls to i2c_smbus_write_byte_data.

> +	for (n = 0; n < NUM_TRIES; n++) {
> +		error = i2c_smbus_write_byte_data(dt->i2c_client, reg, val);
> +		if (error < 0)
> +			dev_err(dev, "i2c_smbus write failed, %d\n", error);
> +		else
> +			return 0;
> +		msleep(10);
> +	}
> +	return error;
> +}
> +
> +static int gp2a_initialize(struct gp2a_data *dt)
> +{
> +	int error;
> +
could do this via a const array and a loop. May not be worth bothering
though..
> +	error = gp2a_write_byte(dt, GP2A_ADDR_GAIN, 0x08);
> +	if (error < 0)
> +		return error;
> +
> +	error = gp2a_write_byte(dt, GP2A_ADDR_HYS, 0xc2);
> +	if (error < 0)
> +		return error;
> +
> +	error = gp2a_write_byte(dt, GP2A_ADDR_CYCLE, 0x04);
> +	if (error < 0)
> +		return error;
> +
> +	error = gp2a_write_byte(dt, GP2A_ADDR_OPMOD, 0x00);
> +
> +	return error;
> +}
> +
> +static int gp2a_report(struct gp2a_data *dt)
> +{
> +	int vo = gpio_get_value(dt->pdata->gpio);
> +
that's a pretty weird bit of distance reporting.  This thing clearly doesn't
report an absolute value, so don't claim it does.
> +	input_report_abs(dt->device, ABS_DISTANCE, vo ? 255 : 0);
> +	input_sync(dt->device);
> +
> +	return 0;
> +}
> +
> +static irqreturn_t gp2a_irq(int irq, void *dev_id)
> +{
> +	struct device *dev = dev_id;
> +	struct gp2a_data *dt = dev_get_drvdata(dev);
> +
> +	gp2a_report(dt);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static int gp2a_device_open(struct input_dev *dev)
> +{
> +	struct gp2a_data *dt = input_get_drvdata(dev);
> +	int error;
> +
> +	error = gp2a_write_byte(dt, GP2A_ADDR_OPMOD, GP2A_CTRL_SSD);
> +	if (error < 0) {
> +		dev_err(&dev->dev, "Unable to activate, err %d\n", error);
> +		return error;
> +	}
> +
irq should be an irq number not a gpio number.

Also, is it worth keeping the irq disabled until here?  What do you
gain?
> +	enable_irq(gpio_to_irq(dt->i2c_client->irq));
> +
> +	if (dt->pdata->wake)
> +		enable_irq_wake(gpio_to_irq(dt->i2c_client->irq));
> +
> +	gp2a_report(dt);
> +
> +	return 0;
> +}
> +
> +static void gp2a_device_close(struct input_dev *dev)
> +{
> +	struct gp2a_data *dt = input_get_drvdata(dev);
> +	int error;
> +
> +	if (dt->pdata->wake)
> +		disable_irq_wake(gpio_to_irq(dt->i2c_client->irq));
> +
> +	disable_irq(gpio_to_irq(dt->i2c_client->irq));
> +	error = gp2a_write_byte(dt, GP2A_ADDR_OPMOD, 0);
> +	if (error < 0)
> +		dev_err(&dev->dev, "Unable to deactivate, err %d\n", error);
> +}
> +
why these definitions?  I guess because you use the driver data
explicitly.  You shouldn't be doing that.
> +static int gp2a_probe(struct i2c_client *client,
> +		      const struct i2c_device_id *id);
> +static int gp2a_remove(struct i2c_client *client);
> +
> +static const struct i2c_device_id gp2a_i2c_id[] = {
> +	{GP2A_I2C_NAME, 0},
> +	{}
> +};
> +
> +static struct i2c_driver gp2a_i2c_driver = {
> +	.driver = {
> +		.name	= GP2A_I2C_NAME,
> +		.owner	= THIS_MODULE
> +	},
> +	.probe		= gp2a_probe,
> +	.remove		= __devexit_p(gp2a_remove),
> +	.id_table	= gp2a_i2c_id
> +};
> +
> +static int gp2a_probe(struct i2c_client *client, const struct i2c_device_id *id)
> +{
> +	struct gp2a_platform_data *pdata;
> +	struct gp2a_data *dt;
> +	int error;
> +
> +	pdata = client->dev.platform_data;
> +	if (!pdata)
> +		return -EINVAL;
> +
give a use case for this please.   Normally once just assumes that
board file or similar has already configured this.  Use gpio_request_one
to wrap up the directly bit as well as do the request.
> +	if (pdata->gpio_setup) {
> +		error = pdata->gpio_setup();
> +		if (error < 0)
> +			return error;
> +	}
> +
> +	error = gpio_direction_input(pdata->gpio);
> +	if (error < 0)
> +		goto err_gpio_shutdown;
> +
> +	dt = kzalloc(sizeof(struct gp2a_data), GFP_KERNEL);
> +	if (!dt) {
> +		error = -ENOMEM;
> +		goto err_gpio_shutdown;
> +	}
> +
??????  that should not be explicitly done.
> +	client->driver = &gp2a_i2c_driver;
> +	dt->pdata = pdata;
> +	dt->i2c_client = client;
> +	i2c_set_clientdata(client, dt);
> +
> +	error = gp2a_initialize(dt);
> +	if (error < 0)
> +		goto err_free_dt;
> +
> +	dt->device = input_allocate_device();
> +	if (!dt->device) {
> +		error = -ENOMEM;
> +		goto err_free_dt;
> +	}
> +
> +	input_set_drvdata(dt->device, dt);
> +
> +	dt->device->open = gp2a_device_open;
> +	dt->device->close = gp2a_device_close;
> +	dt->device->name = GP2A_I2C_NAME;
> +	dt->device->id.bustype = BUS_I2C;
> +	set_bit(EV_ABS, dt->device->evbit);
> +	set_bit(ABS_DISTANCE, dt->device->absbit);
> +
> +	input_set_abs_params(dt->device, ABS_DISTANCE, 0, 255, 0, 0);
> +
> +	error = input_register_device(dt->device);
> +	if (error) {
> +		dev_err(&dt->device->dev, "device registration failed\n");
> +		input_free_device(dt->device);
> +		goto err_free_dt;
> +	}
> +
> +	error = request_threaded_irq(gpio_to_irq(dt->i2c_client->irq), NULL,
> +			gp2a_irq, IRQF_TRIGGER_RISING |
> +			IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
> +			GP2A_I2C_NAME, &dt->i2c_client->dev);
> +	if (error) {
> +		dev_err(&dt->device->dev, "irq request failed\n");
> +		goto err_unreg_input;
> +	}
> +	disable_irq(gpio_to_irq(dt->i2c_client->irq));
> +
> +	return 0;
> +
> +err_unreg_input:
> +	input_unregister_device(dt->device);
> +err_free_dt:
> +	kfree(dt);
> +err_gpio_shutdown:
> +	if (pdata->gpio_shutdown)
> +		pdata->gpio_shutdown();
> +	return error;
> +}
> +
> +static int gp2a_remove(struct i2c_client *client)
> +{
> +	struct gp2a_data *dt = i2c_get_clientdata(client);
> +
> +	device_init_wakeup(&client->dev, 0);
> +	if (dt->pdata->gpio_shutdown)
> +		dt->pdata->gpio_shutdown();
> +	free_irq(gpio_to_irq(dt->i2c_client->irq), &dt->i2c_client->dev);
> +	input_unregister_device(dt->device);
> +	kfree(dt);
> +
> +	return 0;
> +}
> +
> +static int __init gp2a_init(void)
> +{
> +	return i2c_add_driver(&gp2a_i2c_driver);
> +}
> +
> +static void __exit gp2a_exit(void)
> +{
> +	i2c_del_driver(&gp2a_i2c_driver);
> +}
> +
> +module_init(gp2a_init);
> +module_exit(gp2a_exit);
> +
> +MODULE_AUTHOR("Courtney Cavin <courtney.cavin@...yericsson.com>");
> +MODULE_DESCRIPTION("Sharp GP2AP002A00F I2C Proximity/Opto sensor driver");
> +MODULE_LICENSE("GPL v2");
> diff --git a/include/linux/gp2ap002a00f.h b/include/linux/gp2ap002a00f.h
> new file mode 100644
> index 0000000..74e2610
> --- /dev/null
> +++ b/include/linux/gp2ap002a00f.h
> @@ -0,0 +1,13 @@
> +#ifndef _GP2AP002A00F_H_
> +#define _GP2AP002A00F_H_
> +
What is this doing in the header?
> +#define GP2A_I2C_NAME   "gp2ap002a00f"
> +
Document this.  I guess that wake is a bool?
Make it one then.  I'd suggest gpio needs
a more descriptive name as well and the
two gpio functions need a clearly stated reason
for existing.

> +struct gp2a_platform_data {
> +	int gpio;
> +	int wake;
> +	int (*gpio_setup)(void);
> +	int (*gpio_shutdown)(void);
> +};
> +
> +#endif

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