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Date: Wed, 20 Apr 2022 17:55:35 +0000
From: Prashant Malani <pmalani@...omium.org>
To: Fabio Baltieri <fabiobaltieri@...omium.org>
Cc: Benson Leung <bleung@...omium.org>,
Guenter Roeck <groeck@...omium.org>,
Thierry Reding <thierry.reding@...il.com>,
Uwe Kleine-König
<u.kleine-koenig@...gutronix.de>, Lee Jones <lee.jones@...aro.org>,
Rob Herring <robh+dt@...nel.org>,
chrome-platform@...ts.linux.dev, linux-pwm@...r.kernel.org,
devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
Tzung-Bi Shih <tzungbi@...nel.org>
Subject: Re: [PATCH v5 2/4] pwm: pwm-cros-ec: add channel type support
On Apr 20 14:15, Fabio Baltieri wrote:
> Add support for EC_PWM_TYPE_DISPLAY_LIGHT and EC_PWM_TYPE_KB_LIGHT pwm
> types to the PWM cros_ec_pwm driver. This allows specifying one of these
> PWM channel by functionality, and let the EC firmware pick the correct
> channel, thus abstracting the hardware implementation from the kernel
> driver.
>
> To use it, define the node with the "google,cros-ec-pwm-type"
> compatible.
>
> Signed-off-by: Fabio Baltieri <fabiobaltieri@...omium.org>
> Reviewed-by: Tzung-Bi Shih <tzungbi@...nel.org>
> ---
> drivers/pwm/pwm-cros-ec.c | 82 ++++++++++++++++++++++++++++++++-------
> 1 file changed, 67 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/pwm/pwm-cros-ec.c b/drivers/pwm/pwm-cros-ec.c
> index 5e29d9c682c3..7f10f56c3eb6 100644
> --- a/drivers/pwm/pwm-cros-ec.c
> +++ b/drivers/pwm/pwm-cros-ec.c
> @@ -12,17 +12,21 @@
> #include <linux/pwm.h>
> #include <linux/slab.h>
>
> +#include <dt-bindings/mfd/cros_ec.h>
> +
> /**
> * struct cros_ec_pwm_device - Driver data for EC PWM
> *
> * @dev: Device node
> * @ec: Pointer to EC device
> * @chip: PWM controller chip
> + * @use_pwm_type: Use PWM types instead of generic channels
> */
> struct cros_ec_pwm_device {
> struct device *dev;
> struct cros_ec_device *ec;
> struct pwm_chip chip;
> + bool use_pwm_type;
> };
>
> /**
> @@ -58,14 +62,31 @@ static void cros_ec_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
> kfree(channel);
> }
>
> -static int cros_ec_pwm_set_duty(struct cros_ec_device *ec, u8 index, u16 duty)
> +static int cros_ec_dt_type_to_pwm_type(u8 dt_index, u8 *pwm_type)
> {
> + switch (dt_index) {
> + case CROS_EC_PWM_DT_KB_LIGHT:
> + *pwm_type = EC_PWM_TYPE_KB_LIGHT;
> + return 0;
> + case CROS_EC_PWM_DT_DISPLAY_LIGHT:
> + *pwm_type = EC_PWM_TYPE_DISPLAY_LIGHT;
> + return 0;
> + default:
> + return -EINVAL;
> + }
> +}
> +
> +static int cros_ec_pwm_set_duty(struct cros_ec_pwm_device *ec_pwm, u8 index,
> + u16 duty)
> +{
> + struct cros_ec_device *ec = ec_pwm->ec;
> struct {
> struct cros_ec_command msg;
> struct ec_params_pwm_set_duty params;
> } __packed buf;
> struct ec_params_pwm_set_duty *params = &buf.params;
> struct cros_ec_command *msg = &buf.msg;
> + int ret;
>
> memset(&buf, 0, sizeof(buf));
>
> @@ -75,14 +96,25 @@ static int cros_ec_pwm_set_duty(struct cros_ec_device *ec, u8 index, u16 duty)
> msg->outsize = sizeof(*params);
>
> params->duty = duty;
> - params->pwm_type = EC_PWM_TYPE_GENERIC;
> - params->index = index;
> +
> + if (ec_pwm->use_pwm_type) {
> + ret = cros_ec_dt_type_to_pwm_type(index, ¶ms->pwm_type);
> + if (ret) {
> + dev_err(ec->dev, "Invalid PWM type index: %d\n", index);
> + return ret;
> + }
> + params->index = 0;
> + } else {
> + params->pwm_type = EC_PWM_TYPE_GENERIC;
> + params->index = index;
> + }
>
> return cros_ec_cmd_xfer_status(ec, msg);
> }
>
> -static int cros_ec_pwm_get_duty(struct cros_ec_device *ec, u8 index)
> +static int cros_ec_pwm_get_duty(struct cros_ec_pwm_device *ec_pwm, u8 index)
> {
> + struct cros_ec_device *ec = ec_pwm->ec;
> struct {
> struct cros_ec_command msg;
> union {
> @@ -102,8 +134,17 @@ static int cros_ec_pwm_get_duty(struct cros_ec_device *ec, u8 index)
> msg->insize = sizeof(*resp);
> msg->outsize = sizeof(*params);
>
> - params->pwm_type = EC_PWM_TYPE_GENERIC;
> - params->index = index;
> + if (ec_pwm->use_pwm_type) {
> + ret = cros_ec_dt_type_to_pwm_type(index, ¶ms->pwm_type);
> + if (ret) {
> + dev_err(ec->dev, "Invalid PWM type index: %d\n", index);
> + return ret;
> + }
> + params->index = 0;
> + } else {
> + params->pwm_type = EC_PWM_TYPE_GENERIC;
> + params->index = index;
> + }
>
> ret = cros_ec_cmd_xfer_status(ec, msg);
> if (ret < 0)
> @@ -133,7 +174,7 @@ static int cros_ec_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
> */
> duty_cycle = state->enabled ? state->duty_cycle : 0;
>
> - ret = cros_ec_pwm_set_duty(ec_pwm->ec, pwm->hwpwm, duty_cycle);
> + ret = cros_ec_pwm_set_duty(ec_pwm, pwm->hwpwm, duty_cycle);
> if (ret < 0)
> return ret;
>
> @@ -149,7 +190,7 @@ static void cros_ec_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
> struct cros_ec_pwm *channel = pwm_get_chip_data(pwm);
> int ret;
>
> - ret = cros_ec_pwm_get_duty(ec_pwm->ec, pwm->hwpwm);
> + ret = cros_ec_pwm_get_duty(ec_pwm, pwm->hwpwm);
> if (ret < 0) {
> dev_err(chip->dev, "error getting initial duty: %d\n", ret);
> return;
> @@ -204,13 +245,13 @@ static const struct pwm_ops cros_ec_pwm_ops = {
> * of PWMs it supports directly, so we have to read the pwm duty cycle for
> * subsequent channels until we get an error.
> */
> -static int cros_ec_num_pwms(struct cros_ec_device *ec)
> +static int cros_ec_num_pwms(struct cros_ec_pwm_device *ec_pwm)
> {
> int i, ret;
>
> /* The index field is only 8 bits */
> for (i = 0; i <= U8_MAX; i++) {
> - ret = cros_ec_pwm_get_duty(ec, i);
> + ret = cros_ec_pwm_get_duty(ec_pwm, i);
> /*
> * We look for SUCCESS, INVALID_COMMAND, or INVALID_PARAM
> * responses; everything else is treated as an error.
> @@ -236,6 +277,7 @@ static int cros_ec_pwm_probe(struct platform_device *pdev)
> {
> struct cros_ec_device *ec = dev_get_drvdata(pdev->dev.parent);
> struct device *dev = &pdev->dev;
> + struct device_node *np = pdev->dev.of_node;
> struct cros_ec_pwm_device *ec_pwm;
> struct pwm_chip *chip;
> int ret;
> @@ -251,17 +293,26 @@ static int cros_ec_pwm_probe(struct platform_device *pdev)
> chip = &ec_pwm->chip;
> ec_pwm->ec = ec;
>
> + if (of_device_is_compatible(np, "google,cros-ec-pwm-type"))
> + ec_pwm->use_pwm_type = true;
Isn't it possible to just use an optional boolean property
(for example: "use-pwm-type") instead of defining a new compatible
string?
> +
> /* PWM chip */
> chip->dev = dev;
> chip->ops = &cros_ec_pwm_ops;
> chip->of_xlate = cros_ec_pwm_xlate;
> chip->of_pwm_n_cells = 1;
> - ret = cros_ec_num_pwms(ec);
> - if (ret < 0) {
> - dev_err(dev, "Couldn't find PWMs: %d\n", ret);
> - return ret;
> +
> + if (ec_pwm->use_pwm_type) {
> + chip->npwm = CROS_EC_PWM_DT_COUNT;
> + } else {
> + ret = cros_ec_num_pwms(ec_pwm);
> + if (ret < 0) {
> + dev_err(dev, "Couldn't find PWMs: %d\n", ret);
> + return ret;
> + }
> + chip->npwm = ret;
> }
> - chip->npwm = ret;
> +
> dev_dbg(dev, "Probed %u PWMs\n", chip->npwm);
>
> ret = pwmchip_add(chip);
> @@ -288,6 +339,7 @@ static int cros_ec_pwm_remove(struct platform_device *dev)
> #ifdef CONFIG_OF
> static const struct of_device_id cros_ec_pwm_of_match[] = {
> { .compatible = "google,cros-ec-pwm" },
> + { .compatible = "google,cros-ec-pwm-type" },
> {},
> };
> MODULE_DEVICE_TABLE(of, cros_ec_pwm_of_match);
> --
> 2.36.0.rc0.470.gd361397f0d-goog
>
>
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