firmware: raspberrypi: Provide a helper to query a clock max rate

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.

Acked-by: Stephen Boyd <sboyd@kernel.org>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/20220815-rpi-fix-4k-60-v5-3-fe9e7ac8b111@cerno.tech
Signed-off-by: Maxime Ripard <maxime@cerno.tech>

diff --git a/drivers/firmware/raspberrypi.c b/drivers/firmware/raspberrypi.c
index 932a8bef22fbc1c53efc5f2961b0358e4d3ac444..b15aa6fce0e96174cf50e66b63dd60779b2f515d 100644 (file)
--- a/drivers/firmware/raspberrypi.c
+++ b/drivers/firmware/raspberrypi.c
@@ -228,6 +228,26 @@ 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)
+               /*
+                * If our firmware doesn't support that operation, or fails, we
+                * assume the maximum clock rate is absolute maximum we can
+                * store over our type.
+                */
+                return UINT_MAX;
+
+       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 9b1db12d013ff151a0945c4cc6effb2df1894ca4..ab955591cb72c26598676772e3998f7e1e2b268e 100644 (file)
--- a/include/soc/bcm2835/raspberrypi-firmware.h
+++ b/include/soc/bcm2835/raspberrypi-firmware.h
@@ -155,12 +155,32 @@ 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,
@@ -180,6 +200,12 @@ 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;
+}
+
 static inline struct device_node *rpi_firmware_find_node(void)
 {
        return NULL;