linux/drivers/clk/bcm/clk-raspberrypi.c

// SPDX-License-Identifier: GPL-2.0+
/*
 * Raspberry Pi driver for firmware controlled clocks
 *
 * Even though clk-bcm2835 provides an interface to the hardware registers for
 * the system clocks we've had to factor out 'pllb' as the firmware 'owns' it.
 * We're not allowed to change it directly as we might race with the
 * over-temperature and under-voltage protections provided by the firmware.
 *
 * Copyright (C) 2019 Nicolas Saenz Julienne <[email protected]>
 */

#include <linux/clkdev.h>
#include <linux/clk-provider.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/platform_device.h>

#include <soc/bcm2835/raspberrypi-firmware.h>

static char *rpi_firmware_clk_names[] = …;

#define RPI_FIRMWARE_STATE_ENABLE_BIT …
#define RPI_FIRMWARE_STATE_WAIT_BIT …

struct raspberrypi_clk_variant;

struct raspberrypi_clk { … };

struct raspberrypi_clk_data { … };

struct raspberrypi_clk_variant { … };

static struct raspberrypi_clk_variant
raspberrypi_clk_variants[RPI_FIRMWARE_NUM_CLK_ID] = …;

/*
 * Structure of the message passed to Raspberry Pi's firmware in order to
 * change clock rates. The 'disable_turbo' option is only available to the ARM
 * clock (pllb) which we enable by default as turbo mode will alter multiple
 * clocks at once.
 *
 * Even though we're able to access the clock registers directly we're bound to
 * use the firmware interface as the firmware ultimately takes care of
 * mitigating overheating/undervoltage situations and we would be changing
 * frequencies behind his back.
 *
 * For more information on the firmware interface check:
 * https://github.com/raspberrypi/firmware/wiki/Mailbox-property-interface
 */
struct raspberrypi_firmware_prop { … } __packed;

static int raspberrypi_clock_property(struct rpi_firmware *firmware,
				      const struct raspberrypi_clk_data *data,
				      u32 tag, u32 *val)
{ … }

static int raspberrypi_fw_is_prepared(struct clk_hw *hw)
{ … }


static unsigned long raspberrypi_fw_get_rate(struct clk_hw *hw,
					     unsigned long parent_rate)
{ … }

static int raspberrypi_fw_set_rate(struct clk_hw *hw, unsigned long rate,
				   unsigned long parent_rate)
{ … }

static int raspberrypi_fw_dumb_determine_rate(struct clk_hw *hw,
					      struct clk_rate_request *req)
{ … }

static const struct clk_ops raspberrypi_firmware_clk_ops = …;

static struct clk_hw *raspberrypi_clk_register(struct raspberrypi_clk *rpi,
					       unsigned int parent,
					       unsigned int id,
					       struct raspberrypi_clk_variant *variant)
{ … }

struct rpi_firmware_get_clocks_response { … };

static int raspberrypi_discover_clocks(struct raspberrypi_clk *rpi,
				       struct clk_hw_onecell_data *data)
{ … }

static int raspberrypi_clk_probe(struct platform_device *pdev)
{ … }

static void raspberrypi_clk_remove(struct platform_device *pdev)
{ … }

static const struct of_device_id raspberrypi_clk_match[] = …;
MODULE_DEVICE_TABLE(of, raspberrypi_clk_match);

static struct platform_driver raspberrypi_clk_driver = …;
module_platform_driver(…) …;

MODULE_AUTHOR(…) …;
MODULE_DESCRIPTION(…) …;
MODULE_LICENSE(…) …;
MODULE_ALIAS(…) …;