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SubjectRe: [PATCH v2 3/7] firmware: raspberrypi: Provide a helper to query a clock max rate
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Hi Maxime,

Am 20.09.22 um 14:50 schrieb Maxime Ripard:
> The firmware allows to query for its clocks the operating range of a
> given clock. We'll need this for some drivers (KMS, in particular) to
> infer the state of some configuration options, so let's create a
> function to do so.
>
> Signed-off-by: Maxime Ripard <maxime@cerno.tech>
>
> diff --git a/drivers/firmware/raspberrypi.c b/drivers/firmware/raspberrypi.c
> index b916e1e171f8..c4b9ea70f5a7 100644
> --- a/drivers/firmware/raspberrypi.c
> +++ b/drivers/firmware/raspberrypi.c
> @@ -228,6 +228,21 @@ static void rpi_register_clk_driver(struct device *dev)
> -1, NULL, 0);
> }
>
> +unsigned int rpi_firmware_clk_get_max_rate(struct rpi_firmware *fw, unsigned int id)
> +{
> + struct rpi_firmware_clk_rate_request msg =
> + RPI_FIRMWARE_CLK_RATE_REQUEST(id);
> + int ret;
> +
> + ret = rpi_firmware_property(fw, RPI_FIRMWARE_GET_MAX_CLOCK_RATE,
> + &msg, sizeof(msg));
> + if (ret)
> + return 0;
> +
> + return le32_to_cpu(msg.rate);
> +}
> +EXPORT_SYMBOL_GPL(rpi_firmware_clk_get_max_rate);
> +
> static void rpi_firmware_delete(struct kref *kref)
> {
> struct rpi_firmware *fw = container_of(kref, struct rpi_firmware,
> diff --git a/include/soc/bcm2835/raspberrypi-firmware.h b/include/soc/bcm2835/raspberrypi-firmware.h
> index 74c7bcc1ac2a..10248c370229 100644
> --- a/include/soc/bcm2835/raspberrypi-firmware.h
> +++ b/include/soc/bcm2835/raspberrypi-firmware.h
> @@ -154,12 +154,32 @@ enum rpi_firmware_clk_id {
> RPI_FIRMWARE_NUM_CLK_ID,
> };
>
> +/**
> + * struct rpi_firmware_clk_rate_request - Firmware Request for a rate
> + * @id: ID of the clock being queried
> + * @rate: Rate in Hertz. Set by the firmware.
> + *
> + * Used by @RPI_FIRMWARE_GET_CLOCK_RATE, @RPI_FIRMWARE_GET_CLOCK_MEASURED,
> + * @RPI_FIRMWARE_GET_MAX_CLOCK_RATE and @RPI_FIRMWARE_GET_MIN_CLOCK_RATE.
> + */
> +struct rpi_firmware_clk_rate_request {
> + __le32 id;
> + __le32 rate;
> +} __packed;
> +
> +#define RPI_FIRMWARE_CLK_RATE_REQUEST(_id) \
> + { \
> + .id = _id, \
> + }
> +
> #if IS_ENABLED(CONFIG_RASPBERRYPI_FIRMWARE)
> int rpi_firmware_property(struct rpi_firmware *fw,
> u32 tag, void *data, size_t len);
> int rpi_firmware_property_list(struct rpi_firmware *fw,
> void *data, size_t tag_size);
> void rpi_firmware_put(struct rpi_firmware *fw);
> +unsigned int rpi_firmware_clk_get_max_rate(struct rpi_firmware *fw,
> + unsigned int id);
> struct device_node *rpi_firmware_find_node(void);
> struct rpi_firmware *rpi_firmware_get(struct device_node *firmware_node);
> struct rpi_firmware *devm_rpi_firmware_get(struct device *dev,
> @@ -179,6 +199,12 @@ static inline int rpi_firmware_property_list(struct rpi_firmware *fw,
>
> static inline void rpi_firmware_put(struct rpi_firmware *fw) { }
>
> +static inline unsigned int rpi_firmware_clk_get_max_rate(struct rpi_firmware *fw,
> + unsigned int id)
> +{
> + return UINT_MAX;
In case the driver is disabled the function return UINT_MAX, but in case
the firmware doesn't support RPI_FIRMWARE_GET_MAX_CLOCK_RATE it returns
0. This looks a little bit inconsistent to me.
> +}
> +
> static inline struct device_node *rpi_firmware_find_node(void)
> {
> return NULL;
>

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