On Fri, 4 Mar 2016 22:39:06 +0100 Jacek Anaszewski <jacek.anaszewski@xxxxxxxxx> wrote: > On 03/04/2016 08:02 PM, David Rivshin (Allworx) wrote: > > On Fri, 04 Mar 2016 17:01:52 +0100 > > Jacek Anaszewski <j.anaszewski@xxxxxxxxxxx> wrote: > > > >> On 03/04/2016 04:05 PM, David Rivshin (Allworx) wrote: > >>> On Fri, 04 Mar 2016 08:54:02 +0100 > >>> Jacek Anaszewski <j.anaszewski@xxxxxxxxxxx> wrote: > >>> > >>>> On 03/04/2016 01:45 AM, David Rivshin (Allworx) wrote: > >>>>> On Thu, 03 Mar 2016 15:51:32 +0100 > >>>>> Jacek Anaszewski <j.anaszewski@xxxxxxxxxxx> wrote: > >>>>> > >>>>>> Hi David, > >>>>>> > >>>>>> Thanks for the update. Two remarks in the code. > >>>>>> > >>>>>> On 03/03/2016 04:01 AM, David Rivshin (Allworx) wrote: > >>>>>>> From: David Rivshin <drivshin@xxxxxxxxxxx> > >>>>>>> > >>>>>>> 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@xxxxxxxxxxx> > >>>>>>> --- > >>>>>>> > >>>>>>> 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. > >>>>>> > >>>>>> Please adjust the patch so that it compiles without warnings on > >>>>>> current linux-next. Your patch for DT API hasn't been reviewed yet > >>>>>> AFICS, and I can imagine that there will be some resistance against. > >>>>> > >>>>> Since the DT API patch was just accepted by Rob [1], would it be OK > >>>>> to wait for the results of Stefan's testing (and any other reviews) > >>>>> before making a decision on this? From Stefan's note, it won't be > >>>>> until this weekend that he will have a chance to test, and I'm > >>>>> guessing the DT API patch will make its way through Rob's tree to > >>>>> linux-next by then. > >>>> > >>>> OK. > >>>> > >>>>> FYI, the warning workaround would be to make the second parameter to > >>>>> is31fl32xx_parse_child_dt() non-const. > >>>>> > >>>>> [1] https://lkml.org/lkml/2016/3/3/924 > >>>>> > >>>>>>> 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. > >>>>>>> + > >>>>>>> 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 > >>>>>>> + * > >>>>>>> + * 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 > >>>>>>> + */ > >>>>>>> + > >>>>>>> +#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); > >>>>>>> + } > >>>>>>> + 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); > >>>>>> > >>>>>> You seem to call sw_shutdown_func only here, so why should we have > >>>>>> enable parameter in this op? > >>>>> > >>>>> I'm not sure if I understand the question, but I will try to answer. > >>>>> > >>>>> 'enable' is passed through is31fl32xx_software_shutdown to > >>>>> cdef->sw_shutdown_func, so it can be either true or false at that > >>>>> point. The purpose of sw_shutdown_func is to add any special behavior > >>>>> when enabling/disabling software-shutdown mode, which is needed for > >>>>> the 3216 because its SSD bit is in a different position and with > >>>>> opposite polarity. > >>>>> > >>>>> Is it that 'enable' in that line of code makes it look like it's being > >>>>> called with an hardcoded value rather than a variable? If so, perhaps a > >>>>> different parameter name would make it more obvious? Or a kerneldoc > >>>>> comment for the function to describe the parameter? > >>>>> > >>>>> Or have I totally missed the point of the question? > >>>> > >>>> Actually I should have placed this question next to > >>>> the call to s31fl32xx_software_shutdown() in is31fl32xx_init_regs(), > >>>> which is passed "false" in the second argument, and there is no > >>>> other call to s31fl32xx_software_shutdown() in the driver. > >>>> > >>>> Having the argument makes people wondering that there is some > >>>> use case in the driver, where "true" is passed, but it seems not > >>>> to be the case. > >>> > >>> Thanks for the clarification. > >>> > >>> Yes, there is currently no explicit call to enable software-shutdown > >>> mode. Since the reset state of these devices is to have software-shutdown > >>> enabled, the only explicit operation on it that's currently needed is > >>> to disable it. > >>> > >>> Reasons I can think to have the 'enable' parameter anyways include: > >>> - It seems logical to me that an API to manipulate the software-shutdown > >>> state should allow both enabling and disabling. > >>> - Having a parameter for that seemed the most obvious way to go, and it > >>> was trivial to implement. > >>> - Alternatively having separate "enable" and "disable" functions would > >>> duplicate most of the logic, vs the parameter being just a single > >>> conditional. And that would also imply two function pointers in the > >>> chipdefs, which I'd prefer to minimize. > >>> - If anyone wanted to implement suspend/resume in the future, they would > >>> most likely do it by enabling/disabling software-shutdown. Supporting > >>> both enable/disable from the start should make that trivial to do. > >> > >> Suspend/resume callbacks are already implemented in led-class.c and > >> related ops indirectly call brightness_set. If you want to support > >> suspend/resume you have to set LED_CORE_SUSPENDRESUME flag. > > > > If I understand correctly, all LED_CORE_SUSPENDRESUME will do is cause > > the led core to set the brightness to 0 on suspend (and reverse that > > on resume). I see some drivers use this flag and other do not. > > This brings up the question in my mind: how would a driver decide > > whether it is appropriate for an LED to go dark on suspend? Is that > > just the drivers that know the logical purpose of the LEDs they control? > > There is a room for improvement here. Possibly a new LED class sysfs > attribute could be of help in determining that. > > >> Setting brightness to 0 is equivalent to turning the LED controller > >> in a shutdown mode, provided that all sub-LEDs are off. > > > > This is not strictly true for these devices. If someone cared very much > > about power usage when suspended they may want to put the LED controller > > into what it calls "shutdown mode" via the SSD bit. I didn't bother mainly > > because I have no need, and also because I wasn't sure how to even trigger > > a suspend in order to test an implementation. > > I meant that LED class driver should put the device in a software > shutdown mode after last sub-LED is turned off. > > > FYI, I just measured it the effect of software-shutdown even with all LEDs > > already off. The difference in current is about 5mA, measured at the 5V > > supply to a 3216 eval board. Not huge, but someone might care. > > This can be vital difference for some use cases. You could count the > number of currently active sub-LEDs and put the controller in a software > shutdown mode in case the value is 0. I had thought about that, but I had some concerns that dissuaded me from perusing it: - Would need some way to know whether a brightness_set has changed an LED from on->off or off->on in order to update that counter. leds-core modifies led_cdev->brightness before calling brightness_set, so that information would need to be somehow maintained in the driver. - It requires an additional mutex to protect whatever data is involved in the previous bullet. That mutex would need to be taken on every brightness update. - If a single LED is blinking rapidly (e.g. a cpu trigger), it would thrash software shutdown mode. That in turn adds even more CPU usage (due to register writes and mutexes), potentially making power usage worse in some cases. - Time it might take to implement and review (mostly depending on how the first bullet is handled), especially since the 4.6 merge window is fast approaching. That said, I could propose the following simple-to-implement design: - counter, and mutex to protect it, added to 'priv' - previous_brightness field added to 'led_data' - brightness_set compares new brightness vs previous - if on/off state has changed: - takes mutex - updates counter - sets software-shutdown mode to (counter==0) - releases mutex If you think that's worth doing, I can try to get it in along with the other changes for v2. > >>> - I thought the code read better with a bool parameter, vs a longer > >>> function name. > >>> > >>> So nothing really critical, but mostly just my aesthetic and preference. > >>> > >>> Also, I expect that is31fl32xx_software_shutdown() would be inlined, so > >>> the conditional check in there is optimized out anyways, and there is no > >>> performance penalty. Looking at the disassembly in my ARMv7a build, both > >>> of those have indeed happened there. > >> > >> Not only the size of a binary and the performance, but also code > >> readability matters. The function is called only with false argument, > >> so I expect that some people may submit patches optimizing this. > >> > >> Let's avoid the confusion. > > > > I guess we just have a difference of opinion on which way is more > > readable, which is OK. Unless the above explanation causes you to > > change your mind, I will remove the 'enable' parameter and add a > > "_disable" suffix to both functions. That will also leave the > > #define IS31FL32XX_SHUTDOWN_SSD_ENABLE 0 > > constant unused in the code, should that also be removed? Note that > > the 3216 specific constant > > #define IS31FL3216_CONFIG_SSD_ENABLE BIT(7) > > would still be used in is31fl3216_reset(). > > Current version of the function would be required for enabling > shutting down the controller from brightness_set op when the > count of active sub-LEDs drops to 0. Agreed. That's a reason I would have for leaving it so even if the auto-software-shutdown logic is not implemented at this time. But I would understand if you still prefer to only have the current form if there is currently code which uses both possible values of the 'enable' parameter. > >>>>>>> + 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", ®); > >>>>>>> + 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]; > >>>>>>> + 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, > >>>>>>> + .id_table = is31fl31xx_id, > >>>>>>> +}; > >>>>>>> + > >>>>>>> +module_i2c_driver(is31fl32xx_driver); > >>>>>>> + > >>>>>>> +MODULE_AUTHOR("David Rivshin <drivshin@xxxxxxxxxxx>"); > >>>>>>> +MODULE_DESCRIPTION("ISSI IS31FL32xx LED driver"); > >>>>>>> +MODULE_LICENSE("GPL v2"); > >>>>>>> -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
