forked from Minki/linux
LEDS: tca6507 - fix up some comments.
In particular fix the capitalisation of GPIO and LED and correct TCA6507_MAKE_CPIO, but also rewrite the comment about platform-data to include reference to devicetree. Also re-wrap comments to fit 80 columns. Reported-by: Bryan Wu <cooloney@gmail.com> Signed-off-by: NeilBrown <neilb@suse.de> Signed-off-by: Bryan Wu <cooloney@gmail.com>
This commit is contained in:
NeilBrown
Bryan Wu
parent
10ead6e599
commit
1f431afdb4
@ -4,77 +4,87 @@
|
||||
* The TCA6507 is a programmable LED controller that can drive 7
|
||||
* separate lines either by holding them low, or by pulsing them
|
||||
* with modulated width.
|
||||
* The modulation can be varied in a simple pattern to produce a blink or
|
||||
* double-blink.
|
||||
* The modulation can be varied in a simple pattern to produce a
|
||||
* blink or double-blink.
|
||||
*
|
||||
* This driver can configure each line either as a 'GPIO' which is out-only
|
||||
* (no pull-up) or as an LED with variable brightness and hardware-assisted
|
||||
* blinking.
|
||||
* This driver can configure each line either as a 'GPIO' which is
|
||||
* out-only (pull-up resistor required) or as an LED with variable
|
||||
* brightness and hardware-assisted blinking.
|
||||
*
|
||||
* Apart from OFF and ON there are three programmable brightness levels which
|
||||
* can be programmed from 0 to 15 and indicate how many 500usec intervals in
|
||||
* each 8msec that the led is 'on'. The levels are named MASTER, BANK0 and
|
||||
* BANK1.
|
||||
* Apart from OFF and ON there are three programmable brightness
|
||||
* levels which can be programmed from 0 to 15 and indicate how many
|
||||
* 500usec intervals in each 8msec that the led is 'on'. The levels
|
||||
* are named MASTER, BANK0 and BANK1.
|
||||
*
|
||||
* There are two different blink rates that can be programmed, each with
|
||||
* separate time for rise, on, fall, off and second-off. Thus if 3 or more
|
||||
* different non-trivial rates are required, software must be used for the extra
|
||||
* rates. The two different blink rates must align with the two levels BANK0 and
|
||||
* BANK1.
|
||||
* This driver does not support double-blink so 'second-off' always matches
|
||||
* 'off'.
|
||||
* There are two different blink rates that can be programmed, each
|
||||
* with separate time for rise, on, fall, off and second-off. Thus if
|
||||
* 3 or more different non-trivial rates are required, software must
|
||||
* be used for the extra rates. The two different blink rates must
|
||||
* align with the two levels BANK0 and BANK1. This driver does not
|
||||
* support double-blink so 'second-off' always matches 'off'.
|
||||
*
|
||||
* Only 16 different times can be programmed in a roughly logarithmic scale from
|
||||
* 64ms to 16320ms. To be precise the possible times are:
|
||||
* Only 16 different times can be programmed in a roughly logarithmic
|
||||
* scale from 64ms to 16320ms. To be precise the possible times are:
|
||||
* 0, 64, 128, 192, 256, 384, 512, 768,
|
||||
* 1024, 1536, 2048, 3072, 4096, 5760, 8128, 16320
|
||||
*
|
||||
* Times that cannot be closely matched with these must be
|
||||
* handled in software. This driver allows 12.5% error in matching.
|
||||
* Times that cannot be closely matched with these must be handled in
|
||||
* software. This driver allows 12.5% error in matching.
|
||||
*
|
||||
* This driver does not allow rise/fall rates to be set explicitly. When trying
|
||||
* to match a given 'on' or 'off' period, an appropriate pair of 'change' and
|
||||
* 'hold' times are chosen to get a close match. If the target delay is even,
|
||||
* the 'change' number will be the smaller; if odd, the 'hold' number will be
|
||||
* the smaller.
|
||||
* This driver does not allow rise/fall rates to be set explicitly.
|
||||
* When trying to match a given 'on' or 'off' period, an appropriate
|
||||
* pair of 'change' and 'hold' times are chosen to get a close match.
|
||||
* If the target delay is even, the 'change' number will be the
|
||||
* smaller; if odd, the 'hold' number will be the smaller.
|
||||
|
||||
* Choosing pairs of delays with 12.5% errors allows us to match delays in the
|
||||
* ranges: 56-72, 112-144, 168-216, 224-27504, 28560-36720.
|
||||
* 26% of the achievable sums can be matched by multiple pairings. For example
|
||||
* 1536 == 1536+0, 1024+512, or 768+768. This driver will always choose the
|
||||
* pairing with the least maximum - 768+768 in this case. Other pairings are
|
||||
* not available.
|
||||
* Choosing pairs of delays with 12.5% errors allows us to match
|
||||
* delays in the ranges: 56-72, 112-144, 168-216, 224-27504,
|
||||
* 28560-36720.
|
||||
* 26% of the achievable sums can be matched by multiple pairings.
|
||||
* For example 1536 == 1536+0, 1024+512, or 768+768.
|
||||
* This driver will always choose the pairing with the least
|
||||
* maximum - 768+768 in this case. Other pairings are not available.
|
||||
*
|
||||
* Access to the 3 levels and 2 blinks are on a first-come, first-served basis.
|
||||
* Access can be shared by multiple leds if they have the same level and
|
||||
* either same blink rates, or some don't blink.
|
||||
* When a led changes, it relinquishes access and tries again, so it might
|
||||
* lose access to hardware blink.
|
||||
* If a blink engine cannot be allocated, software blink is used.
|
||||
* If the desired brightness cannot be allocated, the closest available non-zero
|
||||
* brightness is used. As 'full' is always available, the worst case would be
|
||||
* to have two different blink rates at '1', with Max at '2', then other leds
|
||||
* will have to choose between '2' and '16'. Hopefully this is not likely.
|
||||
* Access to the 3 levels and 2 blinks are on a first-come,
|
||||
* first-served basis. Access can be shared by multiple leds if they
|
||||
* have the same level and either same blink rates, or some don't
|
||||
* blink. When a led changes, it relinquishes access and tries again,
|
||||
* so it might lose access to hardware blink.
|
||||
*
|
||||
* Each bank (BANK0 and BANK1) has two usage counts - LEDs using the brightness
|
||||
* and LEDs using the blink. It can only be reprogrammed when the appropriate
|
||||
* counter is zero. The MASTER level has a single usage count.
|
||||
* If a blink engine cannot be allocated, software blink is used. If
|
||||
* the desired brightness cannot be allocated, the closest available
|
||||
* non-zero brightness is used. As 'full' is always available, the
|
||||
* worst case would be to have two different blink rates at '1', with
|
||||
* Max at '2', then other leds will have to choose between '2' and
|
||||
* '16'. Hopefully this is not likely.
|
||||
*
|
||||
* Each Led has programmable 'on' and 'off' time as milliseconds. With each
|
||||
* there is a flag saying if it was explicitly requested or defaulted.
|
||||
* Similarly the banks know if each time was explicit or a default. Defaults
|
||||
* are permitted to be changed freely - they are not recognised when matching.
|
||||
* Each bank (BANK0 and BANK1) has two usage counts - LEDs using the
|
||||
* brightness and LEDs using the blink. It can only be reprogrammed
|
||||
* when the appropriate counter is zero. The MASTER level has a
|
||||
* single usage count.
|
||||
*
|
||||
* Each LED has programmable 'on' and 'off' time as milliseconds.
|
||||
* With each there is a flag saying if it was explicitly requested or
|
||||
* defaulted. Similarly the banks know if each time was explicit or a
|
||||
* default. Defaults are permitted to be changed freely - they are
|
||||
* not recognised when matching.
|
||||
*
|
||||
*
|
||||
* An led-tca6507 device must be provided with platform data. This data
|
||||
* lists for each output: the name, default trigger, and whether the signal
|
||||
* is being used as a GPiO rather than an led. 'struct led_plaform_data'
|
||||
* is used for this. If 'name' is NULL, the output isn't used. If 'flags'
|
||||
* is TCA6507_MAKE_CPIO, the output is a GPO.
|
||||
* The "struct led_platform_data" can be embedded in a
|
||||
* "struct tca6507_platform_data" which adds a 'gpio_base' for the GPiOs,
|
||||
* and a 'setup' callback which is called once the GPiOs are available.
|
||||
* An led-tca6507 device must be provided with platform data or
|
||||
* configured via devicetree.
|
||||
*
|
||||
* The platform-data lists for each output: the name, default trigger,
|
||||
* and whether the signal is being used as a GPIO rather than an LED.
|
||||
* 'struct led_plaform_data' is used for this. If 'name' is NULL, the
|
||||
* output isn't used. If 'flags' is TCA6507_MAKE_GPIO, the output is
|
||||
* a GPO. The "struct led_platform_data" can be embedded in a "struct
|
||||
* tca6507_platform_data" which adds a 'gpio_base' for the GPIOs, and
|
||||
* a 'setup' callback which is called once the GPIOs are available.
|
||||
*
|
||||
* When configured via devicetree there is one child for each output.
|
||||
* The "reg" determines the output number and "compatible" determines
|
||||
* whether it is an LED or a GPIO. "linux,default-trigger" can set a
|
||||
* default trigger.
|
||||
*/
|
||||
|
||||
#include <linux/module.h>
|
||||
@ -192,17 +202,18 @@ MODULE_DEVICE_TABLE(i2c, tca6507_id);
|
||||
static int choose_times(int msec, int *c1p, int *c2p)
|
||||
{
|
||||
/*
|
||||
* Choose two timecodes which add to 'msec' as near as possible.
|
||||
* The first returned is the 'on' or 'off' time. The second is to be
|
||||
* used as a 'fade-on' or 'fade-off' time. If 'msec' is even,
|
||||
* the first will not be smaller than the second. If 'msec' is odd,
|
||||
* the first will not be larger than the second.
|
||||
* If we cannot get a sum within 1/8 of 'msec' fail with -EINVAL,
|
||||
* otherwise return the sum that was achieved, plus 1 if the first is
|
||||
* smaller.
|
||||
* If two possibilities are equally good (e.g. 512+0, 256+256), choose
|
||||
* the first pair so there is more change-time visible (i.e. it is
|
||||
* softer).
|
||||
* Choose two timecodes which add to 'msec' as near as
|
||||
* possible. The first returned is the 'on' or 'off' time.
|
||||
* The second is to be used as a 'fade-on' or 'fade-off' time.
|
||||
* If 'msec' is even, the first will not be smaller than the
|
||||
* second. If 'msec' is odd, the first will not be larger
|
||||
* than the second.
|
||||
* If we cannot get a sum within 1/8 of 'msec' fail with
|
||||
* -EINVAL, otherwise return the sum that was achieved, plus 1
|
||||
* if the first is smaller.
|
||||
* If two possibilities are equally good (e.g. 512+0,
|
||||
* 256+256), choose the first pair so there is more
|
||||
* change-time visible (i.e. it is softer).
|
||||
*/
|
||||
int c1, c2;
|
||||
int tmax = msec * 9 / 8;
|
||||
@ -255,8 +266,8 @@ static int choose_times(int msec, int *c1p, int *c2p)
|
||||
}
|
||||
|
||||
/*
|
||||
* Update the register file with the appropriate 3-bit state for
|
||||
* the given led.
|
||||
* Update the register file with the appropriate 3-bit state for the
|
||||
* given led.
|
||||
*/
|
||||
static void set_select(struct tca6507_chip *tca, int led, int val)
|
||||
{
|
||||
@ -274,9 +285,9 @@ static void set_select(struct tca6507_chip *tca, int led, int val)
|
||||
}
|
||||
}
|
||||
|
||||
/* Update the register file with the appropriate 4-bit code for
|
||||
* one bank or other. This can be used for timers, for levels, or
|
||||
* for initialisation.
|
||||
/* Update the register file with the appropriate 4-bit code for one
|
||||
* bank or other. This can be used for timers, for levels, or for
|
||||
* initialization.
|
||||
*/
|
||||
static void set_code(struct tca6507_chip *tca, int reg, int bank, int new)
|
||||
{
|
||||
@ -309,7 +320,7 @@ static void set_level(struct tca6507_chip *tca, int bank, int level)
|
||||
tca->bank[bank].level = level;
|
||||
}
|
||||
|
||||
/* Record all relevant time code for a given bank */
|
||||
/* Record all relevant time codes for a given bank */
|
||||
static void set_times(struct tca6507_chip *tca, int bank)
|
||||
{
|
||||
int c1, c2;
|
||||
@ -317,7 +328,8 @@ static void set_times(struct tca6507_chip *tca, int bank)
|
||||
|
||||
result = choose_times(tca->bank[bank].ontime, &c1, &c2);
|
||||
dev_dbg(&tca->client->dev,
|
||||
"Chose on times %d(%d) %d(%d) for %dms\n", c1, time_codes[c1],
|
||||
"Chose on times %d(%d) %d(%d) for %dms\n",
|
||||
c1, time_codes[c1],
|
||||
c2, time_codes[c2], tca->bank[bank].ontime);
|
||||
set_code(tca, TCA6507_FADE_ON, bank, c2);
|
||||
set_code(tca, TCA6507_FULL_ON, bank, c1);
|
||||
@ -325,7 +337,8 @@ static void set_times(struct tca6507_chip *tca, int bank)
|
||||
|
||||
result = choose_times(tca->bank[bank].offtime, &c1, &c2);
|
||||
dev_dbg(&tca->client->dev,
|
||||
"Chose off times %d(%d) %d(%d) for %dms\n", c1, time_codes[c1],
|
||||
"Chose off times %d(%d) %d(%d) for %dms\n",
|
||||
c1, time_codes[c1],
|
||||
c2, time_codes[c2], tca->bank[bank].offtime);
|
||||
set_code(tca, TCA6507_FADE_OFF, bank, c2);
|
||||
set_code(tca, TCA6507_FIRST_OFF, bank, c1);
|
||||
@ -373,7 +386,8 @@ static void led_release(struct tca6507_led *led)
|
||||
|
||||
static int led_prepare(struct tca6507_led *led)
|
||||
{
|
||||
/* Assign this led to a bank, configuring that bank if necessary. */
|
||||
/* Assign this led to a bank, configuring that bank if
|
||||
* necessary. */
|
||||
int level = TO_LEVEL(led->led_cdev.brightness);
|
||||
struct tca6507_chip *tca = led->chip;
|
||||
int c1, c2;
|
||||
@ -389,10 +403,10 @@ static int led_prepare(struct tca6507_led *led)
|
||||
|
||||
if (led->ontime == 0 || led->offtime == 0) {
|
||||
/*
|
||||
* Just set the brightness, choosing first usable bank.
|
||||
* If none perfect, choose best.
|
||||
* Count backwards so we check MASTER bank first
|
||||
* to avoid wasting a timer.
|
||||
* Just set the brightness, choosing first usable
|
||||
* bank. If none perfect, choose best. Count
|
||||
* backwards so we check MASTER bank first to avoid
|
||||
* wasting a timer.
|
||||
*/
|
||||
int best = -1;/* full-on */
|
||||
int diff = 15-level;
|
||||
@ -433,9 +447,9 @@ static int led_prepare(struct tca6507_led *led)
|
||||
}
|
||||
|
||||
/*
|
||||
* We have on/off time so we need to try to allocate a timing bank.
|
||||
* First check if times are compatible with hardware and give up if
|
||||
* not.
|
||||
* We have on/off time so we need to try to allocate a timing
|
||||
* bank. First check if times are compatible with hardware
|
||||
* and give up if not.
|
||||
*/
|
||||
if (choose_times(led->ontime, &c1, &c2) < 0)
|
||||
return -EINVAL;
|
||||
@ -523,8 +537,8 @@ static int led_assign(struct tca6507_led *led)
|
||||
err = led_prepare(led);
|
||||
if (err) {
|
||||
/*
|
||||
* Can only fail on timer setup. In that case we need to
|
||||
* re-establish as steady level.
|
||||
* Can only fail on timer setup. In that case we need
|
||||
* to re-establish as steady level.
|
||||
*/
|
||||
led->ontime = 0;
|
||||
led->offtime = 0;
|
||||
@ -594,8 +608,8 @@ static void tca6507_gpio_set_value(struct gpio_chip *gc,
|
||||
|
||||
spin_lock_irqsave(&tca->lock, flags);
|
||||
/*
|
||||
* 'OFF' is floating high, and 'ON' is pulled down, so it has the
|
||||
* inverse sense of 'val'.
|
||||
* 'OFF' is floating high, and 'ON' is pulled down, so it has
|
||||
* the inverse sense of 'val'.
|
||||
*/
|
||||
set_select(tca, tca->gpio_map[offset],
|
||||
val ? TCA6507_LS_LED_OFF : TCA6507_LS_LED_ON);
|
||||
|
||||
Loading…
Reference in New Issue
Block a user