pwm: Increse PWM duty resolution to 16bits

The current PWM interface allows for a pwm duty setting ranging from
0 to 100, resulting in a very coarse adjustment. To alleviate the
problem, the interface now allows for a pwm duty setting in the range
of 0 to 65535.

BUG=chromium:615109
BRANCH=None
TEST=Manual on chell.
`ectool pwmsetduty 1 65535` - Verify LCD backlight goes to 100%
`ectool pwmgetduty 1` - Prints 65535
`ectool pwmsetduty 1 0` - Verify LCD backlight goes to 0%
`ectool pwmgetduty 1` - Prints 0

terminal pwmduty tests:
>pwmduty
PWM channels:
  0: 100%
  1: 62%
  2: 100%
  3: 80%
> pwmduty 1 50
Setting channel 1 to 50%
  1: 50%
> pwmduty 1 0
Setting channel 1 to 0%
  1: disabled
> pwmduty 1 100
Setting channel 1 to 100%
  1: 100%
> pwmduty 1 raw 0
Setting channel 1 to raw 0%
  1: disabled
> pwmduty 1 raw 65535
Setting channel 1 to raw 65535%
  1: 65535
> pwmduty
PWM channels:
  0: 100%
  1: 100%
  2: 100%
  3: 80%
> pwmduty 1 raw 30000
Setting channel 1 to raw 30000%
  1: 30000
> pwmduty
PWM channels:
  0: 100%
  1: 46%
  2: 100%
  3: 80%

Change-Id: I299b77585f3988e72d9ac918bdde7dc5fa3df6de
Reviewed-on: https://chromium-review.googlesource.com/374481
Commit-Ready: Shawn N <shawnn@chromium.org>
Tested-by: Sam Hurst <shurst@google.com>
Reviewed-by: Shawn N <shawnn@chromium.org>

1 files changed, 46 insertions, 25 deletions

diff --git a/common/pwm.c b/common/pwm.c
index c7fb627ec7..761d1dad25 100644
--- a/common/pwm.c
+++ b/common/pwm.c
@@ -40,25 +40,30 @@ static int get_target_channel(enum pwm_channel *channel, int type, int index)
 	return *channel >= PWM_CH_COUNT;
 }
 
-/*
- * TODO(crbug.com/615109): These host commands use 16 bit duty cycle, but
- * all of our internal code uses percent on [0, 100]. Convert internal
- * functions to use 16 bit duty and remove the conversions below.
- */
-static int host_command_pwm_set_duty(struct host_cmd_handler_args *args)
+__attribute__((weak)) void pwm_set_raw_duty(enum pwm_channel ch, uint16_t duty)
 {
-	const struct ec_params_pwm_set_duty *p = args->params;
-	enum pwm_channel channel;
 	int percent;
 
 	/* Convert 16 bit duty to percent on [0, 100] */
-	percent = DIV_ROUND_NEAREST(p->duty * 100, EC_PWM_MAX_DUTY);
+	percent = DIV_ROUND_NEAREST((uint32_t)duty * 100, 65535);
+	pwm_set_duty(ch, percent);
+}
+
+__attribute__((weak)) uint16_t pwm_get_raw_duty(enum pwm_channel ch)
+{
+	return (pwm_get_duty(ch) * 65535) / 100;
+}
+
+static int host_command_pwm_set_duty(struct host_cmd_handler_args *args)
+{
+	const struct ec_params_pwm_set_duty *p = args->params;
+	enum pwm_channel channel;
 
 	if (get_target_channel(&channel, p->pwm_type, p->index))
 		return EC_RES_INVALID_PARAM;
 
-	pwm_set_duty(channel, percent);
-	pwm_enable(channel, percent > 0);
+	pwm_set_raw_duty(channel, p->duty);
+	pwm_enable(channel, p->duty > 0);
 
 	return EC_RES_SUCCESS;
 }
@@ -76,8 +81,7 @@ static int host_command_pwm_get_duty(struct host_cmd_handler_args *args)
 	if (get_target_channel(&channel, p->pwm_type, p->index))
 		return EC_RES_INVALID_PARAM;
 
-	/* Convert percent on [0, 100] to 16 bit duty */
-	r->duty = pwm_get_duty(channel) * EC_PWM_MAX_DUTY / 100;
+	r->duty = pwm_get_raw_duty(channel);
 	args->response_size = sizeof(*r);
 
 	return EC_RES_SUCCESS;
@@ -91,24 +95,29 @@ DECLARE_HOST_COMMAND(EC_CMD_PWM_GET_DUTY,
  *
  * @param ch		Channel to print.
  */
-static void print_channel(enum pwm_channel ch)
+static void print_channel(enum pwm_channel ch, int max_duty)
 {
 	if (pwm_get_enabled(ch))
-		ccprintf("  %d: %d%%\n", ch, pwm_get_duty(ch));
+		if (max_duty == 100)
+			ccprintf("  %d: %d%%\n", ch, pwm_get_duty(ch));
+		else
+			ccprintf("  %d: %d\n", ch, pwm_get_raw_duty(ch));
 	else
 		ccprintf("  %d: disabled\n", ch);
 }
 
 static int cc_pwm_duty(int argc, char **argv)
 {
-	int percent = 0;
+	int value = 0;
+	int max_duty = 100;
 	int ch;
 	char *e;
+	char *raw;
 
 	if (argc < 2) {
 		ccprintf("PWM channels:\n");
 		for (ch = 0; ch < PWM_CH_COUNT; ch++)
-			print_channel(ch);
+			print_channel(ch, max_duty);
 		return EC_SUCCESS;
 	}
 
@@ -117,26 +126,38 @@ static int cc_pwm_duty(int argc, char **argv)
 		return EC_ERROR_PARAM1;
 
 	if (argc > 2) {
-		percent = strtoi(argv[2], &e, 0);
-		if (*e || percent > 100) {
+		raw = argv[2];
+		if (!strcasecmp(raw, "raw")) {
+			/* use raw duty */
+			value = strtoi(argv[3], &e, 0);
+			max_duty = EC_PWM_MAX_DUTY;
+		} else {
+			/* use percent duty */
+			value = strtoi(argv[2], &e, 0);
+			max_duty = 100;
+		}
+
+		if (*e || value > max_duty) {
 			/* Bad param */
-			return EC_ERROR_PARAM1;
-		} else if (percent < 0) {
+			return EC_ERROR_PARAM2;
+		} else if (value < 0) {
 			/* Negative = disable */
 			pwm_enable(ch, 0);
 		} else {
-			ccprintf("Setting channel %d to %d%%\n", ch, percent);
+			ccprintf("Setting channel %d to%s%d%%\n",
+				ch, (max_duty == 100) ? " " : " raw ", value);
 			pwm_enable(ch, 1);
-			pwm_set_duty(ch, percent);
+			(max_duty == 100) ? pwm_set_duty(ch, value) :
+				pwm_set_raw_duty(ch, value);
 		}
 	}
 
-	print_channel(ch);
+	print_channel(ch, max_duty);
 
 	return EC_SUCCESS;
 }
 DECLARE_CONSOLE_COMMAND(pwmduty, cc_pwm_duty,
-			"[channel [<percent> | -1=disable]]",
+			"[channel [<percent> | -1=disable] | [raw <value>]]",
 			"Get/set PWM duty cycles ");
 #endif /* CONFIG_PWM */