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From 4c64053e0646f66463bded712d7e6975757cf4c2 Mon Sep 17 00:00:00 2001
From: Maxime Ripard <maxime@cerno.tech>
Date: Tue, 20 Sep 2022 13:49:10 +0200
Subject: [PATCH] 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>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
---
drivers/firmware/raspberrypi.c | 20 +++++++++++++++++
include/soc/bcm2835/raspberrypi-firmware.h | 26 ++++++++++++++++++++++
2 files changed, 46 insertions(+)
--- a/drivers/firmware/raspberrypi.c
+++ b/drivers/firmware/raspberrypi.c
@@ -342,6 +342,26 @@ static void rpi_register_clk_driver(stru
-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,
--- a/include/soc/bcm2835/raspberrypi-firmware.h
+++ b/include/soc/bcm2835/raspberrypi-firmware.h
@@ -181,12 +181,32 @@ enum rpi_firmware_clk_id {
#define GET_DISPLAY_SETTINGS_PAYLOAD_SIZE 64
+/**
+ * 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,
@@ -206,6 +226,12 @@ static inline int rpi_firmware_property_
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;
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