Re: [PATCH 3/4] leds: Add driver for the ISSI IS31FL32xx family of LED controllers

Stefan Wahren
2016-03-03T18:13:38Z

Hi David,

i will test the driver on weekend. Some comments below

> "David Rivshin (Allworx)" <drivshin.allworx@gmail.com> hat am 3. März 2016 um
> 04:01 geschrieben:
>
>
> From: David Rivshin <drivshin@allworx.com>
>
> The IS31FL32xx family of LED controllers are I2C devices with multiple
> constant-current channels, each with independent 256-level PWM control.
>
> Datasheets: http://www.issi.com/US/product-analog-fxled-driver.shtml
>
> This has been tested on the IS31FL3236 and IS31FL3216, on an ARM
> (TI am335x) platform.
>
> The programming paradigm of these devices is similar in the following
> ways:
> - All registers are 8 bit
> - All LED control registers are write-only
> - Each LED channel has a PWM register (0-255)
> - PWM register writes are shadowed until an Update register is poked
> - All have a concept of Software Shutdown, which disables output
>
> However, there are some differences in devices:
> - 3236/3235 have a separate Control register for each LED,
> (3218/3216 pack the enable bits into fewer registers)
> - 3236/3235 have a per-channel current divisor setting
> - 3236/3235 have a Global Control register that can turn off all LEDs
> - 3216 is unique in a number of ways
> - OUT9-OUT16 can be configured as GPIOs instead of LED controls
> - LEDs can be programmed with an 8-frame animation, with
> programmable delay between frames
> - LEDs can be modulated by an input audio signal
> - Max output current can be adjusted from 1/4 to 2x globally
> - Has a Configuration register instead of a Shutdown register
>
> This driver currently only supports the base PWM control function
> of these devices. The following features of these devices are not
> implemented, although it should be possible to add them in the future:
> - All devices are capable of going into a lower-power "software
> shutdown" mode.
> - The is31fl3236 and is31fl3235 can reduce the max output current
> per-channel with a divisor of 1, 2, 3, or 4.
> - The is31fl3216 can use some LED channels as GPIOs instead.
> - The is31fl3216 can animate LEDs in hardware.
> - The is31fl3216 can modulate LEDs according to an audio input.
> - The is31fl3216 can reduce/increase max output current globally.
>
> Signed-off-by: David Rivshin <drivshin@allworx.com>
> ---
>
> You may see two instances of this warning:
> "passing argument 1 of 'of_property_read_string' discards 'const'
> qualifier from pointer target type"
> That is a result of of_property_read_string() taking a non-const
> struct device_node pointer parameter. I have separately submitted a
> patch to fix that [1], and a few related functions which had the same
> issue. I'm hoping that will get into linux-next before this does, so
> that the warnings never show up there.
>
> Changes from RFC:
> - Removed max-brightness DT property.
> - Refer to these devices as "LED controllers" in Kconfig.
> - Removed redundant last sentence from Kconfig entry
> - Removed unnecessary debug code.
> - Do not set led_classdev.brightness to 0 explicitly, as it is
> already initialized to 0 by devm_kzalloc().
> - Used of_property_read_string() instead of of_get_property().
> - Fail immediately on DT parsing error in a child node, rather than
> continuing on with the non-faulty ones.
> - Added additional comments for some things that might be non-obvious.
> - Added constants for the location of the SSD bit in the SHUTDOWN
> register, and the 3216's CONFIG register.
> - Added special sw_shutdown_func for the 3216 device, as that bit
> is in a different register, at a different position, and has reverse
> polarity compared to all the other devices.
> - Refactored is31fl32xx_init_regs() to separate out some logic into
> is31fl32xx_reset_regs() and is31fl32xx_software_shutdown().
>
> [1] https://lkml.org/lkml/2016/3/2/746
>
> drivers/leds/Kconfig | 8 +
> drivers/leds/Makefile | 1 +
> drivers/leds/leds-is31fl32xx.c | 505 +++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 514 insertions(+)
> create mode 100644 drivers/leds/leds-is31fl32xx.c
>
> diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
> index 1034696..9c63ba4 100644
> --- a/drivers/leds/Kconfig
> +++ b/drivers/leds/Kconfig
> @@ -580,6 +580,14 @@ config LEDS_SN3218
> This driver can also be built as a module. If so the module
> will be called leds-sn3218.
>
> +config LEDS_IS31FL32XX
> + tristate "LED support for ISSI IS31FL32XX I2C LED controller family"
> + depends on LEDS_CLASS && I2C && OF
> + help
> + Say Y here to include support for ISSI IS31FL32XX LED controllers.
> + They are I2C devices with multiple constant-current channels, each
> + with independent 256-level PWM control.

Is it worth to mention the module name here?

> +
> comment "LED driver for blink(1) USB RGB LED is under Special HID drivers
> (HID_THINGM)"
>
> config LEDS_BLINKM
> diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
> index 89c9b6f..3fdf313 100644
> --- a/drivers/leds/Makefile
> +++ b/drivers/leds/Makefile
> @@ -67,6 +67,7 @@ obj-$(CONFIG_LEDS_KTD2692) += leds-ktd2692.o
> obj-$(CONFIG_LEDS_POWERNV) += leds-powernv.o
> obj-$(CONFIG_LEDS_SEAD3) += leds-sead3.o
> obj-$(CONFIG_LEDS_SN3218) += leds-sn3218.o
> +obj-$(CONFIG_LEDS_IS31FL32XX) += leds-is31fl32xx.o
>
> # LED SPI Drivers
> obj-$(CONFIG_LEDS_DAC124S085) += leds-dac124s085.o
> diff --git a/drivers/leds/leds-is31fl32xx.c b/drivers/leds/leds-is31fl32xx.c
> new file mode 100644
> index 0000000..49818f0
> --- /dev/null
> +++ b/drivers/leds/leds-is31fl32xx.c
> @@ -0,0 +1,505 @@
> +/*
> + * linux/drivers/leds-is31fl32xx.c

I think this is unnecessary.

> + *
> + * Driver for ISSI IS31FL32xx family of I2C LED controllers
> + *
> + * Copyright 2015 Allworx Corp.
> + *
> + *
> + * 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.
> + *
> + * Datasheets: http://www.issi.com/US/product-analog-fxled-driver.shtml
> + */
> +

Shouldn't we include <linux/device.h> here?

> +#include <linux/err.h>
> +#include <linux/i2c.h>
> +#include <linux/kernel.h>
> +#include <linux/leds.h>
> +#include <linux/module.h>
> +#include <linux/of_platform.h>
> +
> +/* Used to indicate a device has no such register */
> +#define IS31FL32XX_REG_NONE 0xFF
> +
> +/* Software Shutdown bit in Shutdown Register */
> +#define IS31FL32XX_SHUTDOWN_SSD_ENABLE 0
> +#define IS31FL32XX_SHUTDOWN_SSD_DISABLE BIT(0)
> +
> +/* IS31FL3216 has a number of unique registers */
> +#define IS31FL3216_CONFIG_REG 0x00
> +#define IS31FL3216_LIGHTING_EFFECT_REG 0x03
> +#define IS31FL3216_CHANNEL_CONFIG_REG 0x04
> +
> +/* Software Shutdown bit in 3216 Config Register */
> +#define IS31FL3216_CONFIG_SSD_ENABLE BIT(7)
> +#define IS31FL3216_CONFIG_SSD_DISABLE 0
> +
> +struct is31fl32xx_priv;
> +struct is31fl32xx_led_data {
> + struct led_classdev cdev;
> + u8 channel; /* 1-based, max priv->cdef->channels */
> + struct is31fl32xx_priv *priv;
> +};
> +
> +struct is31fl32xx_priv {
> + const struct is31fl32xx_chipdef *cdef;
> + struct i2c_client *client;
> + unsigned int num_leds;
> + struct is31fl32xx_led_data leds[0];
> +};
> +
> +/**
> + * struct is31fl32xx_chipdef - chip-specific attributes
> + * @channels : Number of LED channels
> + * @shutdown_reg : address of Shutdown register (optional)
> + * @pwm_update_reg : address of PWM Update register
> + * @global_control_reg : address of Global Control register (optional)
> + * @reset_reg : address of Reset register (optional)
> + * @pwm_register_base : address of first PWM register
> + * @pwm_registers_reversed: : true if PWM registers count down instead of up
> + * @led_control_register_base : address of first LED control register
> (optional)
> + * @enable_bits_per_led_control_register: number of LEDs enable bits in each
> + * @reset_func: : pointer to reset function
> + *
> + * For all optional register addresses, the sentinel value
> %IS31FL32XX_REG_NONE
> + * indicates that this chip has no such register.
> + *
> + * If non-NULL, @reset_func will be called during probing to set all
> + * necessary registers to a known initialization state. This is needed
> + * for chips that do not have a @reset_reg.
> + *
> + * @enable_bits_per_led_control_register must be >=1 if
> + * @led_control_register_base != %IS31FL32XX_REG_NONE.
> + */
> +struct is31fl32xx_chipdef {
> + u8 channels;
> + u8 shutdown_reg;
> + u8 pwm_update_reg;
> + u8 global_control_reg;
> + u8 reset_reg;
> + u8 pwm_register_base;
> + bool pwm_registers_reversed;
> + u8 led_control_register_base;
> + u8 enable_bits_per_led_control_register;
> + int (*reset_func)(struct is31fl32xx_priv *priv);
> + int (*sw_shutdown_func)(struct is31fl32xx_priv *priv, bool enable);
> +};
> +
> +static const struct is31fl32xx_chipdef is31fl3236_cdef = {
> + .channels = 36,
> + .shutdown_reg = 0x00,
> + .pwm_update_reg = 0x25,
> + .global_control_reg = 0x4a,
> + .reset_reg = 0x4f,
> + .pwm_register_base = 0x01,
> + .led_control_register_base = 0x26,
> + .enable_bits_per_led_control_register = 1,
> +};
> +
> +static const struct is31fl32xx_chipdef is31fl3235_cdef = {
> + .channels = 28,
> + .shutdown_reg = 0x00,
> + .pwm_update_reg = 0x25,
> + .global_control_reg = 0x4a,
> + .reset_reg = 0x4f,
> + .pwm_register_base = 0x05,
> + .led_control_register_base = 0x2a,
> + .enable_bits_per_led_control_register = 1,
> +};
> +
> +static const struct is31fl32xx_chipdef is31fl3218_cdef = {
> + .channels = 18,
> + .shutdown_reg = 0x00,
> + .pwm_update_reg = 0x16,
> + .global_control_reg = IS31FL32XX_REG_NONE,
> + .reset_reg = 0x17,
> + .pwm_register_base = 0x01,
> + .led_control_register_base = 0x13,
> + .enable_bits_per_led_control_register = 6,
> +};
> +
> +static int is31fl3216_reset(struct is31fl32xx_priv *priv);
> +static int is31fl3216_software_shutdown(struct is31fl32xx_priv *priv,
> + bool enable);
> +static const struct is31fl32xx_chipdef is31fl3216_cdef = {
> + .channels = 16,
> + .shutdown_reg = IS31FL32XX_REG_NONE,
> + .pwm_update_reg = 0xB0,
> + .global_control_reg = IS31FL32XX_REG_NONE,
> + .reset_reg = IS31FL32XX_REG_NONE,
> + .pwm_register_base = 0x10,
> + .pwm_registers_reversed = true,
> + .led_control_register_base = 0x01,
> + .enable_bits_per_led_control_register = 8,
> + .reset_func = is31fl3216_reset,
> + .sw_shutdown_func = is31fl3216_software_shutdown,
> +};
> +
> +static int is31fl32xx_write(struct is31fl32xx_priv *priv, u8 reg, u8 val)
> +{
> + int ret;
> +
> + dev_dbg(&priv->client->dev, "writing register 0x%02X=0x%02X", reg, val);
> +
> + ret = i2c_smbus_write_byte_data(priv->client, reg, val);
> + if (ret) {
> + dev_err(&priv->client->dev,
> + "register write to 0x%02X failed (error %d)",
> + reg, ret);
> + }

In case somebody use this driver as heartbeat and writing fails permanently the
log will be flooded.

> + return ret;
> +}
> +
> +/*
> + * Custom reset function for IS31FL3216 because it does not have a RESET
> + * register the way that the other IS31FL32xx chips do. We don't bother
> + * writing the GPIO and animation registers, because the registers we
> + * do write ensure those will have no effect.
> + */
> +static int is31fl3216_reset(struct is31fl32xx_priv *priv)
> +{
> + unsigned int i;
> + int ret;
> +
> + ret = is31fl32xx_write(priv, IS31FL3216_CONFIG_REG,
> + IS31FL3216_CONFIG_SSD_ENABLE);
> + if (ret)
> + return ret;
> + for (i = 0; i < priv->cdef->channels; i++) {
> + ret = is31fl32xx_write(priv, priv->cdef->pwm_register_base+i,
> + 0x00);
> + if (ret)
> + return ret;
> + }
> + ret = is31fl32xx_write(priv, priv->cdef->pwm_update_reg, 0);
> + if (ret)
> + return ret;
> + ret = is31fl32xx_write(priv, IS31FL3216_LIGHTING_EFFECT_REG, 0x00);
> + if (ret)
> + return ret;
> + ret = is31fl32xx_write(priv, IS31FL3216_CHANNEL_CONFIG_REG, 0x00);
> + if (ret)
> + return ret;
> +
> + return 0;
> +}
> +
> +/*
> + * Custom Software-Shutdown function for IS31FL3216 because it does not have
> + * a SHUTDOWN register the way that the other IS31FL32xx chips do.
> + * We don't bother doing a read/modify/write on the CONFIG register because
> + * we only ever use a value of '0' for the other fields in that register.
> + */
> +static int is31fl3216_software_shutdown(struct is31fl32xx_priv *priv,
> + bool enable)
> +{
> + u8 value = enable ? IS31FL3216_CONFIG_SSD_ENABLE :
> + IS31FL3216_CONFIG_SSD_DISABLE;
> +
> + return is31fl32xx_write(priv, IS31FL3216_CONFIG_REG, value);
> +}
> +
> +/*
> + * NOTE: A mutex is not needed in this function because:
> + * - All referenced data is read-only after probe()
> + * - The I2C core has a mutex on to protect the bus
> + * - There are no read/modify/write operations
> + * - Intervening operations between the write of the PWM register
> + * and the Update register are harmless.
> + *
> + * Example:
> + * PWM_REG_1 write 16
> + * UPDATE_REG write 0
> + * PWM_REG_2 write 128
> + * UPDATE_REG write 0
> + * vs:
> + * PWM_REG_1 write 16
> + * PWM_REG_2 write 128
> + * UPDATE_REG write 0
> + * UPDATE_REG write 0
> + * are equivalent. Poking the Update register merely applies all PWM
> + * register writes up to that point.
> + */
> +static int is31fl32xx_brightness_set(struct led_classdev *led_cdev,
> + enum led_brightness brightness)
> +{
> + const struct is31fl32xx_led_data *led_data =
> + container_of(led_cdev, struct is31fl32xx_led_data, cdev);
> + const struct is31fl32xx_chipdef *cdef = led_data->priv->cdef;
> + u8 pwm_register_offset;
> + int ret;
> +
> + dev_dbg(led_cdev->dev, "%s: %d\n", __func__, brightness);
> +
> + /* NOTE: led_data->channel is 1-based */
> + if (cdef->pwm_registers_reversed)
> + pwm_register_offset = cdef->channels - led_data->channel;
> + else
> + pwm_register_offset = led_data->channel - 1;
> +
> + ret = is31fl32xx_write(led_data->priv,
> + cdef->pwm_register_base + pwm_register_offset,
> + brightness);
> + if (ret)
> + return ret;
> +
> + return is31fl32xx_write(led_data->priv, cdef->pwm_update_reg, 0);
> +}
> +
> +static int is31fl32xx_reset_regs(struct is31fl32xx_priv *priv)
> +{
> + const struct is31fl32xx_chipdef *cdef = priv->cdef;
> + int ret;
> +
> + if (cdef->reset_reg != IS31FL32XX_REG_NONE) {
> + ret = is31fl32xx_write(priv, cdef->reset_reg, 0);
> + if (ret)
> + return ret;
> + }
> +
> + if (cdef->reset_func)
> + return cdef->reset_func(priv);
> +
> + return 0;
> +}
> +
> +static int is31fl32xx_software_shutdown(struct is31fl32xx_priv *priv,
> + bool enable)
> +{
> + const struct is31fl32xx_chipdef *cdef = priv->cdef;
> + int ret;
> +
> + if (cdef->shutdown_reg != IS31FL32XX_REG_NONE) {
> + u8 value = enable ? IS31FL32XX_SHUTDOWN_SSD_ENABLE :
> + IS31FL32XX_SHUTDOWN_SSD_DISABLE;
> + ret = is31fl32xx_write(priv, cdef->shutdown_reg, value);
> + if (ret)
> + return ret;
> + }
> +
> + if (cdef->sw_shutdown_func)
> + return cdef->sw_shutdown_func(priv, enable);
> +
> + return 0;
> +}
> +
> +static int is31fl32xx_init_regs(struct is31fl32xx_priv *priv)
> +{
> + const struct is31fl32xx_chipdef *cdef = priv->cdef;
> + int ret;
> +
> + ret = is31fl32xx_reset_regs(priv);
> + if (ret)
> + return ret;
> +
> + /*
> + * Set enable bit for all channels.
> + * We will control state with PWM registers alone.
> + */
> + if (cdef->led_control_register_base != IS31FL32XX_REG_NONE) {
> + u8 value =
> + GENMASK(cdef->enable_bits_per_led_control_register-1, 0);
> + u8 num_regs = cdef->channels /
> + cdef->enable_bits_per_led_control_register;
> + int i;
> +
> + for (i = 0; i < num_regs; i++) {
> + ret = is31fl32xx_write(priv,
> + cdef->led_control_register_base+i,
> + value);
> + if (ret)
> + return ret;
> + }
> + }
> +
> + ret = is31fl32xx_software_shutdown(priv, false);
> + if (ret)
> + return ret;
> +
> + if (cdef->global_control_reg != IS31FL32XX_REG_NONE) {
> + ret = is31fl32xx_write(priv, cdef->global_control_reg, 0x00);
> + if (ret)
> + return ret;
> + }
> +
> + return 0;
> +}
> +
> +static inline size_t sizeof_is31fl32xx_priv(int num_leds)
> +{
> + return sizeof(struct is31fl32xx_priv) +
> + (sizeof(struct is31fl32xx_led_data) * num_leds);
> +}
> +
> +static int is31fl32xx_parse_child_dt(const struct device *dev,
> + const struct device_node *child,
> + struct is31fl32xx_led_data *led_data)
> +{
> + struct led_classdev *cdev = &led_data->cdev;
> + int ret = 0;
> + u32 reg;
> +
> + if (of_property_read_string(child, "label", &cdev->name))
> + cdev->name = child->name;
> +
> + ret = of_property_read_u32(child, "reg", &reg);
> + if (ret || reg < 1 || reg > led_data->priv->cdef->channels) {
> + dev_err(dev,
> + "Child node %s does not have a valid reg property\n",
> + child->full_name);
> + return -EINVAL;
> + }
> + led_data->channel = reg;
> +
> + of_property_read_string(child, "linux,default-trigger",
> + &cdev->default_trigger);
> +
> + cdev->brightness_set_blocking = is31fl32xx_brightness_set;
> +
> + return 0;
> +}
> +
> +static struct is31fl32xx_led_data *is31fl32xx_find_led_data(
> + struct is31fl32xx_priv *priv,
> + u8 channel)
> +{
> + size_t i;
> +
> + for (i = 0; i < priv->num_leds; i++) {
> + if (priv->leds[i].channel == channel)
> + return &priv->leds[i];
> + }
> +
> + return NULL;
> +}
> +
> +static int is31fl32xx_parse_dt(struct device *dev,
> + struct is31fl32xx_priv *priv)
> +{
> + struct device_node *child;
> + int ret = 0;
> +
> + for_each_child_of_node(dev->of_node, child) {
> + struct is31fl32xx_led_data *led_data =
> + &priv->leds[priv->num_leds];

Maybe i missed something, but is it really protected against out of index
access?

> + const struct is31fl32xx_led_data *other_led_data;
> +
> + led_data->priv = priv;
> +
> + ret = is31fl32xx_parse_child_dt(dev, child, led_data);
> + if (ret)
> + goto err;
> +
> + /* Detect if channel is already in use by another child */
> + other_led_data = is31fl32xx_find_led_data(priv,
> + led_data->channel);
> + if (other_led_data) {
> + dev_err(dev,
> + "%s and %s both attempting to use channel %d\n",
> + led_data->cdev.name,
> + other_led_data->cdev.name,
> + led_data->channel);
> + goto err;
> + }
> +
> + ret = devm_led_classdev_register(dev, &led_data->cdev);
> + if (ret) {
> + dev_err(dev, "failed to register PWM led for %s: %d\n",
> + led_data->cdev.name, ret);
> + goto err;
> + }
> +
> + priv->num_leds++;
> + }
> +
> + return 0;
> +
> +err:
> + of_node_put(child);
> + return ret;
> +}
> +
> +static const struct of_device_id of_is31fl31xx_match[] = {
> + { .compatible = "issi,is31fl3236", .data = &is31fl3236_cdef, },
> + { .compatible = "issi,is31fl3235", .data = &is31fl3235_cdef, },
> + { .compatible = "issi,is31fl3218", .data = &is31fl3218_cdef, },
> + { .compatible = "issi,is31fl3216", .data = &is31fl3216_cdef, },
> + {},
> +};
> +
> +MODULE_DEVICE_TABLE(of, of_is31fl31xx_match);
> +
> +static int is31fl32xx_probe(struct i2c_client *client,
> + const struct i2c_device_id *id)
> +{
> + const struct is31fl32xx_chipdef *cdef;
> + const struct of_device_id *of_dev_id;
> + struct device *dev = &client->dev;
> + struct is31fl32xx_priv *priv;
> + int count;
> + int ret = 0;
> +
> + of_dev_id = of_match_device(of_is31fl31xx_match, dev);
> + if (!of_dev_id)
> + return -EINVAL;
> +
> + cdef = of_dev_id->data;
> +
> + count = of_get_child_count(dev->of_node);
> + if (!count)
> + return -EINVAL;
> +
> + priv = devm_kzalloc(dev, sizeof_is31fl32xx_priv(count),
> + GFP_KERNEL);
> + if (!priv)
> + return -ENOMEM;
> +
> + priv->client = client;
> + priv->cdef = cdef;
> + i2c_set_clientdata(client, priv);
> +
> + ret = is31fl32xx_init_regs(priv);
> + if (ret)
> + return ret;
> +
> + ret = is31fl32xx_parse_dt(dev, priv);
> + if (ret)
> + return ret;
> +
> + return 0;
> +}
> +
> +static int is31fl32xx_remove(struct i2c_client *client)
> +{
> + struct is31fl32xx_priv *priv = i2c_get_clientdata(client);
> +
> + return is31fl32xx_reset_regs(priv);
> +}
> +
> +/*
> + * i2c-core requires that id_table be non-NULL, even though
> + * it is not used for DeviceTree based instantiation.
> + */
> +static const struct i2c_device_id is31fl31xx_id[] = {
> + {},
> +};
> +
> +MODULE_DEVICE_TABLE(i2c, is31fl31xx_id);
> +
> +static struct i2c_driver is31fl32xx_driver = {
> + .driver = {
> + .name = "is31fl32xx",
> + .of_match_table = of_is31fl31xx_match,
> + },
> + .probe = is31fl32xx_probe,
> + .remove = is31fl32xx_remove,

Sorry, what was the reason to skip shutdown?

Thanks
Stefan

> + .id_table = is31fl31xx_id,
> +};
> +
> +module_i2c_driver(is31fl32xx_driver);
> +
> +MODULE_AUTHOR("David Rivshin <drivshin@allworx.com>");
> +MODULE_DESCRIPTION("ISSI IS31FL32xx LED driver");
> +MODULE_LICENSE("GPL v2");
> --
> 2.5.0
>