Re: [RFC 1/2] backlight: add new tps611xx backlight driver

From: Jingoo Han
Date: Mon Jun 16 2014 - 08:19:29 EST

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On Monday, June 16, 2014 11:17 AM, Daniel Jeong wrote:
>
> This driver a general version for tps611xx backlgiht chips of TI.
> It supports tps61158, tps61161, tps61163 and tps61165 backlight driver
> based on EasyScale protocol.

"EasyScale" protocol is a TI-specific protocol. How about adding more
detailed description as below? I referred to the datasheet of tps61158.

based on EasyScale protocol (1-Wire Control Interface). The protocol
consists of a device specific address byte and a data byte. The device
specific address byte is fixed to 58 hex. The data byte consists of
five bits for information, two address bits ("00"), and the RFA bit.

>
> Signed-off-by: Daniel Jeong <gshark.jeong@xxxxxxxxx>
> ---
> drivers/video/backlight/Kconfig | 7 +
> drivers/video/backlight/Makefile | 1 +
> drivers/video/backlight/tps611xx_bl.c | 486 +++++++++++++++++++++++++++++
> include/linux/platform_data/tps611xx_bl.h | 30 ++
> 4 files changed, 524 insertions(+)
> create mode 100644 drivers/video/backlight/tps611xx_bl.c
> create mode 100644 include/linux/platform_data/tps611xx_bl.h
>
> diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig
> index 5a3eb2e..c779a85 100644
> --- a/drivers/video/backlight/Kconfig
> +++ b/drivers/video/backlight/Kconfig
> @@ -418,6 +418,13 @@ config BACKLIGHT_TPS65217
> If you have a Texas Instruments TPS65217 say Y to enable the
> backlight driver.
>
> +config BACKLIGHT_TPS611xx
> + tristate "TPS611xx Backlight"
> + depends on BACKLIGHT_CLASS_DEVICE && GPIOLIB
> + help
> + This supports TI TPS61158, TPS61161, TPS61163 and TPS61165
> + backlight driver based on EasyScale Protocol.
> +
> config BACKLIGHT_AS3711
> tristate "AS3711 Backlight"
> depends on BACKLIGHT_CLASS_DEVICE && MFD_AS3711
> diff --git a/drivers/video/backlight/Makefile b/drivers/video/backlight/Makefile
> index bb82002..44f1641 100644
> --- a/drivers/video/backlight/Makefile
> +++ b/drivers/video/backlight/Makefile
> @@ -52,4 +52,5 @@ obj-$(CONFIG_BACKLIGHT_PWM) += pwm_bl.o
> obj-$(CONFIG_BACKLIGHT_SAHARA) += kb3886_bl.o
> obj-$(CONFIG_BACKLIGHT_TOSA) += tosa_bl.o
> obj-$(CONFIG_BACKLIGHT_TPS65217) += tps65217_bl.o
> +obj-$(CONFIG_BACKLIGHT_TPS611xx) += tps611xx_bl.o
> obj-$(CONFIG_BACKLIGHT_WM831X) += wm831x_bl.o
> diff --git a/drivers/video/backlight/tps611xx_bl.c b/drivers/video/backlight/tps611xx_bl.c
> new file mode 100644
> index 0000000..4b76cdd
> --- /dev/null
> +++ b/drivers/video/backlight/tps611xx_bl.c
> @@ -0,0 +1,486 @@
> +/*
> + * Simple driver for Texas Instruments TPS611XX Backlight driver chip
> + * using EasyScale Interface. It supports TPS61158, TPS61161,
> + * TPS61163 and TPS61165.
> + *
> + * Copyright (C) 2014 Texas Instruments
> + * Author: Daniel Jeong <gshark.jeong@xxxxxxxxx>
> + * Ldd Mlp <ldd-mlp@xxxxxxxxxxx>
> + *
> + * 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/backlight.h>
> +#include <linux/delay.h>
> +#include <linux/err.h>
> +#include <linux/fb.h>
> +#include <linux/gpio.h>
> +#include <linux/init.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_device.h>
> +#include <linux/platform_data/tps611xx_bl.h>
> +#include <linux/platform_device.h>
> +#include <linux/slab.h>
> +
> +#define CMD_FORWARD 0
> +#define CMD_BACKWARD 1
> +
> +enum tps611xx_id {
> + TPS61158_ID = 0,
> + TPS61161_ID,
> + TPS61163_ID,
> + TPS61165_ID,
> +};
> +
> +/*
> + * easyscale time spec
> + * @es_delay : es delay time(ns)
> + * @es_det : es detection time(ns)
> + * @start : start time of data stream(ns)
> + * @eos : end time of data stream(ns)
> + * @reset : ic shutdown time(ms)
> + * @logic_1_low : low time high bit(ns)
> + * @logic_0_low : low time low bit(ns)
> + * @ackn : duation of ack condistion(ns)
> + * @ack_poll : ack polling duration(ns)
> + */
> +struct tps611xx_time {
> + unsigned int es_delay;
> + unsigned int es_det;
> + unsigned int start;
> + unsigned int eos;
> + unsigned int reset;
> + unsigned int logic_1_low;
> + unsigned int logic_0_low;
> + unsigned int ackn;
> + unsigned int ack_poll;
> +};
> +
> +/*
> + * @seq : sequence of data transfer
> + * @size: size of data
> + * @brt_max : max brightness
> + * @brt_bmask : bit mask of dimming bits
> + * @rfa_bmask : bit mask of request of ack

s/request of ack/request for ack ?

> + */
> +struct tps611xx_command {
> + int seq;
> + int size;
> + int brt_max;
> + int brt_bmask;
> + int rfa_bmask;
> +};
> +
> +/*
> + * @id : product id
> + * @name : product name
> + * @addr : device address
> + * @cmd : es command info
> + * @time : es time info
> + */
> +struct tps611xx_esdata {
> + enum tps611xx_id id;
> + char *name;
> + int addr;
> + struct tps611xx_command cmd;
> + struct tps611xx_time time;
> +};
> +
> +struct tps611xx_bl_data {
> + struct device *dev;
> + struct backlight_device *bled;
> + struct tps611xx_platform_data *pdata;
> +
> + /*
> + * @rfa_en : acknowlege request enable

s/acknowledge/acknowledge

How about the following?

+ * @rfa_en : request for acknowledge enable

> + * @en_gpio: enable pin gpio no.
> + * @esdata : easyscale data
> + */
> + int rfa_en;
> + unsigned int en_gpio;
> + const struct tps611xx_esdata *esdata;
> +};
> +
> +static struct tps611xx_esdata tps611xx_info[] = {
> + [TPS61158_ID] = {
> + .id = TPS61158_ID,
> + .name = "tps61158",
> + .addr = 0x5800,
> + .cmd = {
> + .seq = CMD_FORWARD,
> + .size = 16,
> + .brt_max = 31,
> + .brt_bmask = 0x1f,
> + .rfa_bmask = 0x80},

Would you keep the coding style? The following looks better.

+ .rfa_bmask = 0x80
+ },

> + .time = {
> + .es_delay = 100000,
> + .es_det = 450000,
> + .start = 3500,
> + .eos = 3500,
> + .reset = 4,
> + .logic_1_low = 5000,
> + .logic_0_low = 15000,
> + .ackn = 900000,
> + .ack_poll = 2000},
> + },
> +
> + [TPS61161_ID] = {
> + .id = TPS61161_ID,
> + .name = "tps61161",
> + .addr = 0x7200,
> + .cmd = {
> + .seq = CMD_FORWARD,
> + .size = 16,
> + .brt_max = 31,
> + .brt_bmask = 0x1f,
> + .rfa_bmask = 0x80},
> + .time = {
> + .es_delay = 120000,
> + .es_det = 280000,
> + .start = 2000,
> + .eos = 2000,
> + .reset = 3,
> + .logic_1_low = 3000,
> + .logic_0_low = 7000,
> + .ackn = 512000,
> + .ack_poll = 2000},
> + },
> +
> + [TPS61163_ID] = {
> + .id = TPS61163_ID,
> + .name = "tps61163",
> + .addr = 0x8F0000,
> + .cmd = {
> + .seq = CMD_BACKWARD,
> + .size = 24,
> + .brt_max = 511,
> + .brt_bmask = 0x1ff,
> + .rfa_bmask = 0x400},
> + .time = {
> + .es_delay = 100000,
> + .es_det = 260000,
> + .start = 2000,
> + .eos = 2000,
> + .reset = 3,
> + .logic_1_low = 3000,
> + .logic_0_low = 7000,
> + .ackn = 512000,
> + .ack_poll = 2000},
> + },
> +
> + [TPS61165_ID] = {
> + .id = TPS61165_ID,
> + .name = "tps61165",
> + .addr = 0x7200,
> + .cmd = {
> + .seq = CMD_FORWARD,
> + .size = 16,
> + .brt_max = 31,
> + .brt_bmask = 0x1f,
> + .rfa_bmask = 0x80},
> + .time = {
> + .es_delay = 120000,
> + .es_det = 280000,
> + .start = 4000,
> + .eos = 4000,
> + .reset = 3,
> + .logic_1_low = 3000,
> + .logic_0_low = 7000,
> + .ackn = 512000,
> + .ack_poll = 2000},
> + },
> +};
> +
> +static int tps611xx_bl_update_status(struct backlight_device *bl)
> +{
> + struct tps611xx_bl_data *pchip = bl_get_data(bl);
> + const struct tps611xx_esdata *esdata = pchip->esdata;
> + int data_in, t_low, t_logic, max_bmask;
> + unsigned long flags;
> +
> + data_in = esdata->addr | (bl->props.brightness & esdata->cmd.brt_bmask);
> + if (pchip->rfa_en)
> + data_in |= esdata->cmd.rfa_bmask;
> +
> + max_bmask = 0x1 << esdata->cmd.size;
> + t_logic = esdata->time.logic_1_low + esdata->time.logic_0_low;
> +
> + local_irq_save(flags);
> + /* t_start : 2us high before data byte */
> + gpio_direction_output(pchip->en_gpio, 1);
> + ndelay(esdata->time.start);
> +
> + /* forward command transfer */
> + if (esdata->cmd.seq == CMD_FORWARD) {
> + int addr_bmask = max_bmask >> 8;
> +
> + for (max_bmask >>= 1; max_bmask > 0x0; max_bmask >>= 1) {
> + if (data_in & max_bmask)
> + t_low = esdata->time.logic_1_low;
> + else
> + t_low = esdata->time.logic_0_low;
> +
> + gpio_direction_output(pchip->en_gpio, 0);
> + ndelay(t_low);
> + gpio_direction_output(pchip->en_gpio, 1);
> + ndelay(t_logic - t_low);
> +
> + if (max_bmask == addr_bmask) {
> + gpio_direction_output(pchip->en_gpio, 0);
> + /* t_eos : low after address byte */
> + ndelay(esdata->time.eos);
> + gpio_direction_output(pchip->en_gpio, 1);
> + /* t_start : high before data byte */
> + ndelay(esdata->time.start);
> + }
> + }
> + } else {
> + /* backward command tansfer */
> + int bmask;
> +
> + for (bmask = 0x01; bmask < max_bmask; bmask <<= 1) {
> + if (data_in & bmask)
> + t_low = esdata->time.logic_1_low;
> + else
> + t_low = esdata->time.logic_0_low;
> +
> + gpio_direction_output(pchip->en_gpio, 0);
> + ndelay(t_low);
> + gpio_direction_output(pchip->en_gpio, 1);
> + ndelay(t_logic - t_low);
> + }
> + }
> +
> + /*
> + * t_eos : low after address byte
> + * t_ackVal is also t_eos
> + */
> + gpio_direction_output(pchip->en_gpio, 0);
> + ndelay(esdata->time.eos);
> +
> + /* RFA management */
> + if (pchip->rfa_en) {
> + int max_ack_time = esdata->time.ackn;
> + /* set input */
> + gpio_direction_input(pchip->en_gpio);
> + /* read acknowledge from chip */
> + while (max_ack_time > 0) {
> + if (gpio_get_value(pchip->en_gpio) == 0)
> + break;
> + max_ack_time -= esdata->time.ack_poll;
> + }
> + if (max_ack_time <= 0)
> + dev_err(pchip->dev,
> + "easyscale : no ack from %s\n", esdata->name);
> + else
> + ndelay(max_ack_time);
> + }
> + gpio_direction_output(pchip->en_gpio, 1);
> + local_irq_restore(flags);
> +
> + return bl->props.brightness;
> +}
> +
> +static int tps611xx_bl_get_brightness(struct backlight_device *bl)
> +{
> + return bl->props.brightness;
> +}
> +
> +static const struct backlight_ops tps611xx_bl_ops = {
> + .update_status = tps611xx_bl_update_status,
> + .get_brightness = tps611xx_bl_get_brightness,
> +};
> +
> +static ssize_t tps611xx_enable_store(struct device *dev,
> + struct device_attribute *devAttr,
> + const char *buf, size_t size)
> +{
> + struct tps611xx_bl_data *pchip = dev_get_drvdata(dev);
> + const struct tps611xx_esdata *esdata = pchip->esdata;
> + unsigned long flags;
> + unsigned int input;
> + int ret;
> +
> + ret = kstrtouint(buf, 10, &input);
> + if (ret)
> + return -EINVAL;
> +
> + local_irq_save(flags);
> + if (input == 0) {
> + /* chip disable */
> + gpio_direction_output(pchip->en_gpio, 0);
> + /* low more than reset ms to reset */
> + mdelay(esdata->time.reset);
> + } else {
> + /* easyscale detection window */
> + gpio_direction_output(pchip->en_gpio, 1);
> + ndelay(esdata->time.es_delay);
> + gpio_direction_output(pchip->en_gpio, 0);
> + ndelay(esdata->time.es_det);
> + gpio_direction_output(pchip->en_gpio, 1);
> + }
> + local_irq_restore(flags);
> +
> + return size;
> +}
> +
> +static DEVICE_ATTR(enable, S_IWUSR, NULL, tps611xx_enable_store);
> +
> +#ifdef CONFIG_OF
> +static struct of_device_id tps611xx_backlight_of_match[] = {

Please add 'const' as below.

+static const struct of_device_id tps611xx_backlight_of_match[] = {

> + {.compatible = "ti,tps61158_bl", .data = &tps611xx_info[TPS61158_ID]},
> + {.compatible = "ti,tps61161_bl", .data = &tps611xx_info[TPS61161_ID]},
> + {.compatible = "ti,tps61163_bl", .data = &tps611xx_info[TPS61163_ID]},
> + {.compatible = "ti,tps61165_bl", .data = &tps611xx_info[TPS61165_ID]},
> + {}
> +};
> +
> +MODULE_DEVICE_TABLE(of, tps611xx_backlight_of_match);
> +
> +static int tps611xx_backlight_parse_dt(struct tps611xx_bl_data *pchip)
> +{
> + struct device *dev = pchip->dev;
> + struct device_node *node = dev->of_node;
> + const struct of_device_id *of_id =
> + of_match_device(tps611xx_backlight_of_match, dev);
> + u32 value;
> + int ret;
> +
> + if (!node)
> + return -ENODEV;
> +
> + if (!of_id || !of_id->data) {
> + dev_err(dev, "Failed to find tps611xx chip id\n");
> + return -EFAULT;
> + }
> + pchip->esdata = of_id->data;
> +
> + ret = of_property_read_u32(node, "en_gpio_num", &value);
> + if (ret < 0)
> + return ret;
> + pchip->en_gpio = value;
> + ret = of_property_read_u32(node, "rfa_en", &value);
> + if (ret < 0)
> + return ret;
> + pchip->rfa_en = value;
> +
> + return 0;
> +}
> +#else
> +static int tps611xx_backlight_parse_dt(struct tps611xx_bl_data *pchip)
> +{
> + return -ENODEV;
> +}
> +#endif
> +
> +static int tps611xx_backlight_probe(struct platform_device *pdev)
> +{
> + struct tps611xx_bl_data *pchip;
> + struct backlight_properties props;
> + const struct tps611xx_esdata *esdata;
> + struct tps611xx_platform_data *pdata = dev_get_platdata(&pdev->dev);
> + unsigned long flags;
> + int ret;
> +
> + pchip = devm_kzalloc(&pdev->dev,
> + sizeof(struct tps611xx_bl_data), GFP_KERNEL);
> + if (pchip == NULL)
> + return -ENOMEM;
> + pchip->dev = &pdev->dev;
> +
> + if (pdata == NULL) {
> + ret = tps611xx_backlight_parse_dt(pchip);
> + if (ret < 0)
> + return ret;
> + } else {
> + pchip->rfa_en = pdata->rfa_en;
> + pchip->en_gpio = pdata->en_gpio_num;
> + pchip->esdata = (const struct tps611xx_esdata *)
> + platform_get_device_id(pdev)->driver_data;
> + }
> + esdata = pchip->esdata;
> +
> + memset(&props, 0, sizeof(struct backlight_properties));
> + props.brightness = esdata->cmd.brt_max;
> + props.max_brightness = esdata->cmd.brt_max;
> + props.type = BACKLIGHT_RAW;
> + pchip->bled =
> + devm_backlight_device_register(pchip->dev, TPS611XX_NAME,
> + pchip->dev, pchip,
> + &tps611xx_bl_ops, &props);
> + if (IS_ERR(pchip->bled))
> + return PTR_ERR(pchip->bled);
> +
> + /* for enable/disable */
> + ret = device_create_file(&(pchip->bled->dev), &dev_attr_enable);
> + if (ret < 0) {
> + dev_err(pchip->dev, "failed : add sysfs entries\n");
> + return ret;
> + }
> + platform_set_drvdata(pdev, pchip);
> +
> + /* EasyScale init */
> + ret = gpio_request_one(pchip->en_gpio, GPIOF_OUT_INIT_HIGH, "tps611xx");
> + if (ret) {
> + device_remove_file(&(pchip->bled->dev), &dev_attr_enable);
> + dev_err(pchip->dev, "failed : get gpio %d\n", pchip->en_gpio);
> + return ret;
> + }
> +
> + /*
> + * ES Detection Window
> + * - ES detect delay
> + * - ES detect time
> + */
> + local_irq_save(flags);
> + gpio_direction_output(pchip->en_gpio, 1);
> + ndelay(esdata->time.es_delay);
> + gpio_direction_output(pchip->en_gpio, 0);
> + ndelay(esdata->time.es_det);
> + gpio_direction_output(pchip->en_gpio, 1);
> + local_irq_restore(flags);
> + dev_info(pchip->dev,
> + "%s EasyScale is initialized\n", pchip->esdata->name);
> + return 0;
> +}
> +
> +static int tps611xx_backlight_remove(struct platform_device *pdev)
> +{
> + struct tps611xx_bl_data *pchip = platform_get_drvdata(pdev);
> + const struct tps611xx_esdata *esdata = pchip->esdata;
> +
> + device_remove_file(&(pchip->bled->dev), &dev_attr_enable);
> + gpio_direction_output(pchip->en_gpio, 0);
> + mdelay(esdata->time.reset);
> + return 0;
> +}
> +
> +static const struct platform_device_id tps611xx_id_table[] = {
> + {TPS61158_NAME, (unsigned long)&tps611xx_info[TPS61158_ID]},
> + {TPS61161_NAME, (unsigned long)&tps611xx_info[TPS61161_ID]},
> + {TPS61163_NAME, (unsigned long)&tps611xx_info[TPS61163_ID]},
> + {TPS61165_NAME, (unsigned long)&tps611xx_info[TPS61165_ID]},
> + {}
> +};
> +
> +static struct platform_driver tps611xx_backlight_driver = {
> + .driver = {
> + .name = TPS611XX_NAME,
> + .owner = THIS_MODULE,
> + .of_match_table = of_match_ptr(tps611xx_backlight_of_match),
> + },
> + .probe = tps611xx_backlight_probe,
> + .remove = tps611xx_backlight_remove,
> + .id_table = tps611xx_id_table,
> +};
> +
> +module_platform_driver(tps611xx_backlight_driver);
> +
> +MODULE_DESCRIPTION("EasyScale based tps611xx Backlight Driver");
> +MODULE_LICENSE("GPL");

How about adding 'GPL v2' instead of 'GPL'?

+ MODULE_LICENSE("GPL v2");

> +MODULE_ALIAS("platform:tps611xx_bl");
> diff --git a/include/linux/platform_data/tps611xx_bl.h b/include/linux/platform_data/tps611xx_bl.h
> new file mode 100644
> index 0000000..b7c4504
> --- /dev/null
> +++ b/include/linux/platform_data/tps611xx_bl.h
> @@ -0,0 +1,30 @@
> +/*
> + * Simple driver for Texas Instruments TPS61163a Backlight driver chip
> + * Copyright (C) 2014 Texas Instruments
> + *
> + * 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 __TPS611XX_H
> +#define __TPS611XX_H
> +
> +#define TPS611XX_NAME "tps611xx_bl"
> +#define TPS61158_NAME "tps61158_bl"
> +#define TPS61161_NAME "tps61161_bl"
> +#define TPS61163_NAME "tps61163_bl"
> +#define TPS61165_NAME "tps61165_bl"
> +
> +/* struct tps61163a platform data

Please use the proper coding style as below.

+/*
+ * struct tps61163a platform data

> + * @rfa_en : request for acknowledge
> + * @en_gpio_num : gpio number for en_pin
> + */
> +struct tps611xx_platform_data {
> +
> + int rfa_en;
> + unsigned int en_gpio_num;
> +};
> +
> +#endif /* __TPS61163A_H */

s/__TPS61163A_H/__TPS611XX_H

Best regards,
Jingoo Han

> --
> 1.7.9.5

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