Date:	Wed, 17 Jul 2013 12:20:33 +0100
From:	Lee Jones <lee.jones@...aro.org>
To:	"Kim, Milo" <Milo.Kim@...com>
Cc:	"sameo@...ux.intel.com" <sameo@...ux.intel.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-pwm@...r.kernel.org" <linux-pwm@...r.kernel.org>,
	"thierry.reding@...il.com" <thierry.reding@...il.com>,
	"grant.likely@...aro.org" <grant.likely@...aro.org>,
	"linus.walleij@...aro.org" <linus.walleij@...aro.org>,
	broonie@...nel.org
Subject: Re: [PATCH 1/3] mfd: add LP3943 MFD driver

This driver is heavily regmap based, so I think it would make sense
for Mark Brown to glance over it briefly.

> LP3943 has 16 output LED channels which can be used as GPIO expander and
> PWM generators.
> This patch supports the MFD structure of those features.
> 
> * Regmap I2C interface for R/W LP3943 registers
> 
> * Device tree bindings updated
>   PWM generator output ports can be defined in the platform data.
>   Those are configurable with the DT structure as well.
> 
> Signed-off-by: Milo Kim <milo.kim@...com>
> ---
>  Documentation/devicetree/bindings/mfd/lp3943.txt |   23 +++
>  drivers/mfd/Kconfig                              |    8 +
>  drivers/mfd/Makefile                             |    1 +
>  drivers/mfd/lp3943.c                             |  206 ++++++++++++++++++++++
>  include/linux/mfd/lp3943.h                       |   98 ++++++++++
>  5 files changed, 336 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/mfd/lp3943.txt
>  create mode 100644 drivers/mfd/lp3943.c
>  create mode 100644 include/linux/mfd/lp3943.h
> 
> diff --git a/Documentation/devicetree/bindings/mfd/lp3943.txt b/Documentation/devicetree/bindings/mfd/lp3943.txt
> new file mode 100644
> index 0000000..4eb251d
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/mfd/lp3943.txt
> @@ -0,0 +1,23 @@
> +Bindings for TI/National Semiconductor LP3943 Driver
> +
> +Required properties:
> +  - compatible: "ti,lp3943"
> +  - reg: 7bit I2C slave address. 0x60 ~ 0x67
> +
> +Optional properties:
> +  - ti,pwm0, ti,pwm1: Output channel definition for PWM port 0 and 1
> +                      0 = invalid, 1 = LED0, 2 = LED 1, ... 16 = LED15
                                         No space here ^      ^ comma here

This is actually pretty confusing. 

Any way you can put the invalid entry at the end so, 0 == LED0?

> +Datasheet
> +  http://www.ti.com/lit/ds/snvs256b/snvs256b.pdf

Ah, I see.... So the above are pins, rather than arbitrary channel Nos.

Would it make sense to use pinctrl instead then?

> +Application note: How to use LP3943 as a GPIO expander and PWM generator
> +  http://www.ti.com/lit/an/snva287a/snva287a.pdf
> +
> +Example:
> +
> +	lp3943@60 {
> +		compatible = "ti,lp3943";
> +		reg = <0x60>;
> +		pwm1 = /bits/ 8 <2>;	/* use LED1 output as PWM #1 */
> +	};
> diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
> index ff553ba..cf9b943 100644
> --- a/drivers/mfd/Kconfig
> +++ b/drivers/mfd/Kconfig
> @@ -506,6 +506,14 @@ config PMIC_ADP5520
>  	  individual components like LCD backlight, LEDs, GPIOs and Kepad
>  	  under the corresponding menus.
>  
> +config MFD_LP3943
> +	tristate "TI/National Semiconductor LP3943 MFD Driver"
> +	depends on I2C
> +	select MFD_CORE
> +	select REGMAP_I2C
> +	help
> +	  TI LP3943 supports a GPIO expander and two PWM generators.
> +
>  config MFD_LP8788
>  	bool "Texas Instruments LP8788 Power Management Unit Driver"
>  	depends on I2C=y
> diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
> index 8b977f8..8f129a4 100644
> --- a/drivers/mfd/Makefile
> +++ b/drivers/mfd/Makefile
> @@ -96,6 +96,7 @@ obj-$(CONFIG_PMIC_DA9052)	+= da9052-core.o
>  obj-$(CONFIG_MFD_DA9052_SPI)	+= da9052-spi.o
>  obj-$(CONFIG_MFD_DA9052_I2C)	+= da9052-i2c.o
>  
> +obj-$(CONFIG_MFD_LP3943)	+= lp3943.o
>  obj-$(CONFIG_MFD_LP8788)	+= lp8788.o lp8788-irq.o
>  
>  da9055-objs			:= da9055-core.o da9055-i2c.o
> diff --git a/drivers/mfd/lp3943.c b/drivers/mfd/lp3943.c
> new file mode 100644
> index 0000000..6d31066
> --- /dev/null
> +++ b/drivers/mfd/lp3943.c
> @@ -0,0 +1,206 @@
> +/*
> + * TI/National Semiconductor LP3943 MFD Core Driver
> + *
> + * Copyright 2013 Texas Instruments
> + *
> + * Author: Milo(Woogyom) Kim <milo.kim@...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/err.h>
> +#include <linux/gpio.h>
> +#include <linux/i2c.h>
> +#include <linux/mfd/core.h>
> +#include <linux/mfd/lp3943.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_gpio.h>
> +#include <linux/slab.h>
> +
> +#define LP3943_MAX_REGISTERS		0x09
> +
> +/* Register configuration for pin MUX */
> +static const struct lp3943_reg_cfg lp3943_mux_cfg[16] = {
> +	/* address, mask, shift */
> +	{ LP3943_REG_MUX0, 0x03, 0 },
> +	{ LP3943_REG_MUX0, 0x0C, 2 },
> +	{ LP3943_REG_MUX0, 0x30, 4 },
> +	{ LP3943_REG_MUX0, 0xC0, 6 },
> +	{ LP3943_REG_MUX1, 0x03, 0 },
> +	{ LP3943_REG_MUX1, 0x0C, 2 },
> +	{ LP3943_REG_MUX1, 0x30, 4 },
> +	{ LP3943_REG_MUX1, 0xC0, 6 },
> +	{ LP3943_REG_MUX2, 0x03, 0 },
> +	{ LP3943_REG_MUX2, 0x0C, 2 },
> +	{ LP3943_REG_MUX2, 0x30, 4 },
> +	{ LP3943_REG_MUX2, 0xC0, 6 },
> +	{ LP3943_REG_MUX3, 0x03, 0 },
> +	{ LP3943_REG_MUX3, 0x0C, 2 },
> +	{ LP3943_REG_MUX3, 0x30, 4 },
> +	{ LP3943_REG_MUX3, 0xC0, 6 },
> +};
> +
> +static struct mfd_cell lp3943_devs[] = {
> +	{
> +		.name = "lp3943-pwm",
> +	},
> +	{
> +		.name = "lp3943-gpio",
> +	},
> +};
> +
> +int lp3943_read_byte(struct lp3943 *l, u8 reg, u8 *read)

Not sure I like 'l' as a variable name. The function is small enough
to get away with it in this context, but it would probably be better
if it were renamed to something more meaningful. 

> +{
> +	int ret;
> +	unsigned int val;
> +
> +	ret = regmap_read(l->regmap, reg, &val);
> +	if (ret < 0) {
> +		dev_err(l->dev, "failed to read 0x%.2x\n", reg);
> +		return ret;
> +	}
> +
> +	*read = (u8)val;
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(lp3943_read_byte);
> +
> +int lp3943_write_byte(struct lp3943 *l, u8 reg, u8 data)
> +{
> +	return regmap_write(l->regmap, reg, data);
> +}
> +EXPORT_SYMBOL_GPL(lp3943_write_byte);
> +
> +int lp3943_update_bits(struct lp3943 *l, u8 reg, u8 mask, u8 data)
> +{
> +	return regmap_update_bits(l->regmap, reg, mask, data);
> +}
> +EXPORT_SYMBOL_GPL(lp3943_update_bits);
> +
> +#ifdef CONFIG_OF
> +static int lp3943_parse_dt(struct device *dev, struct device_node *node)
> +{
> +	struct lp3943_platform_data *pdata;
> +	u8 port = 0;
> +
> +	if (!node) {
> +		dev_err(dev, "no platform data\n");
> +		return -EINVAL;
> +	}
> +
> +	pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL);
> +	if (!pdata)
> +		return -ENOMEM;
> +
> +	of_property_read_u8(node, "ti,pwm0", &port);
> +	pdata->pwm0 = (enum lp3943_pwm_output)port;
> +	port = 0;
> +	of_property_read_u8(node, "ti,pwm1", &port);
> +	pdata->pwm1 = (enum lp3943_pwm_output)port;
> +
> +	dev->platform_data = pdata;
> +	return 0;
> +}
> +#else
> +static int lp3943_parse_dt(struct device *dev, struct device_node *node)
> +{
> +	return -EINVAL;
> +}
> +#endif
> +
> +static const struct regmap_config lp3943_regmap_config = {
> +	.reg_bits = 8,
> +	.val_bits = 8,
> +	.max_register = LP3943_MAX_REGISTERS,
> +};
> +
> +static int lp3943_probe(struct i2c_client *cl, const struct i2c_device_id *id)
> +{
> +	struct lp3943_platform_data *pdata;
> +	struct lp3943 *l;
> +	int err;
> +
> +	if (!cl->dev.platform_data) {
> +		err = lp3943_parse_dt(&cl->dev, cl->dev.of_node);
> +		if (err)
> +			return err;
> +	}
> +
> +	pdata = cl->dev.platform_data;
> +
> +	l = devm_kzalloc(&cl->dev, sizeof(struct lp3943), GFP_KERNEL);
> +	if (!l)
> +		return -ENOMEM;
> +
> +	l->regmap = devm_regmap_init_i2c(cl, &lp3943_regmap_config);
> +	if (IS_ERR(l->regmap)) {
> +		err = PTR_ERR(l->regmap);
> +		dev_err(&cl->dev, "regmap init i2c err: %d\n", err);
> +		return err;
> +	}
> +
> +	l->pdata = pdata;
> +	l->dev = &cl->dev;
> +	l->mux_cfg = lp3943_mux_cfg;
> +	i2c_set_clientdata(cl, l);
> +
> +	err = mfd_add_devices(l->dev, -1, lp3943_devs, ARRAY_SIZE(lp3943_devs),
> +			NULL, 0, NULL);
> +	if (err) {
> +		dev_err(l->dev, "add device err: %d\n", err);
> +		return err;
> +	}
> +
> +	return 0;
> +}
> +
> +static int lp3943_remove(struct i2c_client *cl)
> +{
> +	struct lp3943 *l = i2c_get_clientdata(cl);
> +
> +	mfd_remove_devices(l->dev);
> +	return 0;
> +}
> +
> +static const struct i2c_device_id lp3943_ids[] = {
> +	{"lp3943", 0},

Lack of consistency ...

> +	{ }
> +};
> +MODULE_DEVICE_TABLE(i2c, lp3943_ids);
> +
> +static const struct of_device_id lp3943_dt_ids[] = {
> +	{ .compatible = "ti,lp3943", },

... with this one. Personally, I prefer this one.

> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, lp3943_dt_ids);
> +
> +static struct i2c_driver lp3943_driver = {
> +	.driver = {
> +		.name = "lp3943",
> +		.owner = THIS_MODULE,
> +		.of_match_table = of_match_ptr(lp3943_dt_ids),
> +	},
> +	.probe = lp3943_probe,
> +	.remove = lp3943_remove,
> +	.id_table = lp3943_ids,
> +};
> +
> +static int __init lp3943_init(void)
> +{
> +	return i2c_add_driver(&lp3943_driver);
> +}
> +subsys_initcall(lp3943_init);
> +
> +static void __exit lp3943_exit(void)
> +{
> +	i2c_del_driver(&lp3943_driver);
> +}
> +module_exit(lp3943_exit);
> +
> +MODULE_DESCRIPTION("TI LP3943 MFD Core Driver");
> +MODULE_AUTHOR("Milo Kim");
> +MODULE_LICENSE("GPL");
> diff --git a/include/linux/mfd/lp3943.h b/include/linux/mfd/lp3943.h
> new file mode 100644
> index 0000000..208fc73
> --- /dev/null
> +++ b/include/linux/mfd/lp3943.h
> @@ -0,0 +1,98 @@
> +/*
> + * TI/National Semiconductor LP3943 Device
> + *
> + * Copyright 2013 Texas Instruments
> + *
> + * Author: Milo(Woogyom) Kim <milo.kim@...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.
> + *
> + */
> +
> +#ifndef __MFD_LP3943_H__
> +#define __MFD_LP3943_H__
> +
> +#include <linux/gpio.h>
> +#include <linux/pwm.h>
> +#include <linux/regmap.h>
> +
> +/* Registers */
> +#define LP3943_REG_GPIO_A		0x00
> +#define LP3943_REG_GPIO_B		0x01
> +#define LP3943_REG_PRESCALE0		0x02
> +#define LP3943_REG_PWM0			0x03
> +#define LP3943_REG_PRESCALE1		0x04
> +#define LP3943_REG_PWM1			0x05
> +#define LP3943_REG_MUX0			0x06
> +#define LP3943_REG_MUX1			0x07
> +#define LP3943_REG_MUX2			0x08
> +#define LP3943_REG_MUX3			0x09
> +
> +/* Bit description for LP3943_REG_MUX0 ~ 3 */
> +#define LP3943_GPIO_IN			0x00
> +#define LP3943_GPIO_OUT_HIGH		0x00
> +#define LP3943_GPIO_OUT_LOW		0x01
> +#define LP3943_DIM_PWM0			0x02
> +#define LP3943_DIM_PWM1			0x03
> +
> +enum lp3943_pwm_output {
> +	LP3943_PWM_INVALID,
> +	LP3943_PWM_LED0,
> +	LP3943_PWM_LED1,
> +	LP3943_PWM_LED2,
> +	LP3943_PWM_LED3,
> +	LP3943_PWM_LED4,
> +	LP3943_PWM_LED5,
> +	LP3943_PWM_LED6,
> +	LP3943_PWM_LED7,
> +	LP3943_PWM_LED8,
> +	LP3943_PWM_LED9,
> +	LP3943_PWM_LED10,
> +	LP3943_PWM_LED11,
> +	LP3943_PWM_LED12,
> +	LP3943_PWM_LED13,
> +	LP3943_PWM_LED14,
> +	LP3943_PWM_LED15,
> +};
> +
> +/**
> + * struct lp3943_platform_data
> + * @pwm0: LED output channel definition for PWM 0 port
> + * @pwm1: LED output channel definition for PWM 1 port
> + */
> +struct lp3943_platform_data {
> +	enum lp3943_pwm_output pwm0;
> +	enum lp3943_pwm_output pwm1;
> +};
> +
> +/*
> + * struct lp3943_reg_cfg
> + * @reg: Register address
> + * @mask: Register bit mask to be updated
> + * @shift: Register bit shift
> + */
> +struct lp3943_reg_cfg {
> +	u8 reg;
> +	u8 mask;
> +	u8 shift;
> +};
> +
> +/*
> + * struct lp3943
> + * @dev: Parent device pointer
> + * @regmap: Used for i2c communcation on accessing registers
> + * @pdata: LP3943 platform specific data
> + */
> +struct lp3943 {
> +	struct device *dev;
> +	struct regmap *regmap;
> +	struct lp3943_platform_data *pdata;
> +	const struct lp3943_reg_cfg *mux_cfg;
> +};
> +
> +int lp3943_read_byte(struct lp3943 *lm, u8 reg, u8 *read);
> +int lp3943_write_byte(struct lp3943 *lm, u8 reg, u8 data);
> +int lp3943_update_bits(struct lp3943 *lm, u8 reg, u8 mask, u8 data);
> +#endif

-- 
Lee Jones
Linaro ST-Ericsson Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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