pwm: Modify new PWM host commands to take 16-bit duty cycle

EC_CMD_PWM_SET_DUTY / EC_CMD_PWM_GET_DUTY were recently added and are
not yet in use. Future-proof these commands by taking a 16-bit duty
cycle parameter and converting it between the [0-100] percent used by
internal EC functions.

BUG=chromium:615109
BRANCH=None
TEST=Manual on chell.
`ectool pwmsetduty kb 65535` - Verify KB backlight goes to 100%
`ectool pwmgetduty kb` - Prints 65535
`ectool pwmgetduty 0` - Prints 65535
`ectool pwmsetduty 0 0` - Verify KB backlight goes to 0%
`ectool pwmgetduty kb` - Prints 0
`ectool pwmgetduty disp` - Error res 3 (unsupported PWM type)
`ectool pwmsetduty 1` - Error res 3 (non-existent PWM index)
`ectool pwmsetduty kb 6550` +
`ectool pwmgetduty kb` - Prints 6553 (round up)
`ectool pwmsetduty kb 6560` +
`ectool pwmgetduty kb` - Prints 6553 (round down)

Signed-off-by: Shawn Nematbakhsh <shawnn@chromium.org>
Change-Id: Ic6996fc6e1e69359274b2f9a1120ee7002db991c
Reviewed-on: https://chromium-review.googlesource.com/347608
Commit-Ready: Shawn N <shawnn@chromium.org>
Tested-by: Shawn N <shawnn@chromium.org>
Tested-by: Brian Norris <briannorris@chromium.org>
Reviewed-by: Randall Spangler <rspangler@chromium.org>
Reviewed-by: Brian Norris <briannorris@chromium.org>

1 files changed, 12 insertions, 5 deletions

diff --git a/common/pwm.c b/common/pwm.c
index c689b0acac..84e242abf4 100644
--- a/common/pwm.c
+++ b/common/pwm.c
@@ -40,19 +40,25 @@ 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)
 {
 	const struct ec_params_pwm_set_duty *p = args->params;
 	enum pwm_channel channel;
+	int percent;
 
-	if (p->percent > 100)
-		return EC_RES_INVALID_PARAM;
+	/* Convert 16 bit duty to percent on [0, 100] */
+	percent = DIV_ROUND_NEAREST(p->duty * 100, EC_PWM_MAX_DUTY);
 
 	if (get_target_channel(&channel, p->pwm_type, p->index))
 		return EC_RES_INVALID_PARAM;
 
-	pwm_set_duty(channel, p->percent);
-	pwm_enable(channel, p->percent > 0);
+	pwm_set_duty(channel, percent);
+	pwm_enable(channel, percent > 0);
 
 	return EC_RES_SUCCESS;
 }
@@ -70,7 +76,8 @@ 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;
 
-	r->percent = pwm_get_duty(channel);
+	/* Convert percent on [0, 100] to 16 bit duty */
+	r->duty = pwm_get_duty(channel) * EC_PWM_MAX_DUTY / 100;
 	args->response_size = sizeof(*r);
 
 	return EC_RES_SUCCESS;