drivers/clk/bcm/clk-raspberrypi.c - linux - Git at Google

 // 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 <nsaenzjulienne@suse.de>
  */

 #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>

 #define RPI_FIRMWARE_ARM_CLK_ID		0x00000003

 #define RPI_FIRMWARE_STATE_ENABLE_BIT	BIT(0)
 #define RPI_FIRMWARE_STATE_WAIT_BIT	BIT(1)

 /*
  * Even though the firmware interface alters 'pllb' the frequencies are
  * provided as per 'pllb_arm'. We need to scale before passing them trough.
  */
 #define RPI_FIRMWARE_PLLB_ARM_DIV_RATE	2

 #define A2W_PLL_FRAC_BITS		20

 struct raspberrypi_clk {
 	struct device *dev;
 	struct rpi_firmware *firmware;
 	struct platform_device *cpufreq;

 	unsigned long min_rate;
 	unsigned long max_rate;

 	struct clk_hw pllb;
 	struct clk_hw *pllb_arm;
 	struct clk_lookup *pllb_arm_lookup;
 };

 /*
  * 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 {
 	__le32 id;
 	__le32 val;
 	__le32 disable_turbo;
 } __packed;

 static int raspberrypi_clock_property(struct rpi_firmware *firmware, u32 tag,
 				      u32 clk, u32 *val)
 {
 	struct raspberrypi_firmware_prop msg = {
 		.id = cpu_to_le32(clk),
 		.val = cpu_to_le32(*val),
 		.disable_turbo = cpu_to_le32(1),
 	};
 	int ret;

 	ret = rpi_firmware_property(firmware, tag, &msg, sizeof(msg));
 	if (ret)
 		return ret;

 	*val = le32_to_cpu(msg.val);

 	return 0;
 }

 static int raspberrypi_fw_pll_is_on(struct clk_hw *hw)
 {
 	struct raspberrypi_clk *rpi = container_of(hw, struct raspberrypi_clk,
 						   pllb);
 	u32 val = 0;
 	int ret;

 	ret = raspberrypi_clock_property(rpi->firmware,
 					 RPI_FIRMWARE_GET_CLOCK_STATE,
 					 RPI_FIRMWARE_ARM_CLK_ID, &val);
 	if (ret)
 		return 0;

 	return !!(val & RPI_FIRMWARE_STATE_ENABLE_BIT);
 }


 static unsigned long raspberrypi_fw_pll_get_rate(struct clk_hw *hw,
 						 unsigned long parent_rate)
 {
 	struct raspberrypi_clk *rpi = container_of(hw, struct raspberrypi_clk,
 						   pllb);
 	u32 val = 0;
 	int ret;

 	ret = raspberrypi_clock_property(rpi->firmware,
 					 RPI_FIRMWARE_GET_CLOCK_RATE,
 					 RPI_FIRMWARE_ARM_CLK_ID,
 					 &val);
 	if (ret)
 		return ret;

 	return val * RPI_FIRMWARE_PLLB_ARM_DIV_RATE;
 }

 static int raspberrypi_fw_pll_set_rate(struct clk_hw *hw, unsigned long rate,
 				       unsigned long parent_rate)
 {
 	struct raspberrypi_clk *rpi = container_of(hw, struct raspberrypi_clk,
 						   pllb);
 	u32 new_rate = rate / RPI_FIRMWARE_PLLB_ARM_DIV_RATE;
 	int ret;

 	ret = raspberrypi_clock_property(rpi->firmware,
 					 RPI_FIRMWARE_SET_CLOCK_RATE,
 					 RPI_FIRMWARE_ARM_CLK_ID,
 					 &new_rate);
 	if (ret)
 		dev_err_ratelimited(rpi->dev, "Failed to change %s frequency: %d",
 				    clk_hw_get_name(hw), ret);

 	return ret;
 }

 /*
  * Sadly there is no firmware rate rounding interface. We borrowed it from
  * clk-bcm2835.
  */
 static int raspberrypi_pll_determine_rate(struct clk_hw *hw,
 					  struct clk_rate_request *req)
 {
 	struct raspberrypi_clk *rpi = container_of(hw, struct raspberrypi_clk,
 						   pllb);
 	u64 div, final_rate;
 	u32 ndiv, fdiv;

 	/* We can't use req->rate directly as it would overflow */
 	final_rate = clamp(req->rate, rpi->min_rate, rpi->max_rate);

 	div = (u64)final_rate << A2W_PLL_FRAC_BITS;
 	do_div(div, req->best_parent_rate);

 	ndiv = div >> A2W_PLL_FRAC_BITS;
 	fdiv = div & ((1 << A2W_PLL_FRAC_BITS) - 1);

 	final_rate = ((u64)req->best_parent_rate *
 					((ndiv << A2W_PLL_FRAC_BITS) + fdiv));

 	req->rate = final_rate >> A2W_PLL_FRAC_BITS;

 	return 0;
 }

 static const struct clk_ops raspberrypi_firmware_pll_clk_ops = {
 	.is_prepared = raspberrypi_fw_pll_is_on,
 	.recalc_rate = raspberrypi_fw_pll_get_rate,
 	.set_rate = raspberrypi_fw_pll_set_rate,
 	.determine_rate = raspberrypi_pll_determine_rate,
 };

 static int raspberrypi_register_pllb(struct raspberrypi_clk *rpi)
 {
 	u32 min_rate = 0, max_rate = 0;
 	struct clk_init_data init;
 	int ret;

 	memset(&init, 0, sizeof(init));

 	/* All of the PLLs derive from the external oscillator. */
 	init.parent_names = (const char *[]){ "osc" };
 	init.num_parents = 1;
 	init.name = "pllb";
 	init.ops = &raspberrypi_firmware_pll_clk_ops;
 	init.flags = CLK_GET_RATE_NOCACHE | CLK_IGNORE_UNUSED;

 	/* Get min & max rates set by the firmware */
 	ret = raspberrypi_clock_property(rpi->firmware,
 					 RPI_FIRMWARE_GET_MIN_CLOCK_RATE,
 					 RPI_FIRMWARE_ARM_CLK_ID,
 					 &min_rate);
 	if (ret) {
 		dev_err(rpi->dev, "Failed to get %s min freq: %d\n",
 			init.name, ret);
 		return ret;
 	}

 	ret = raspberrypi_clock_property(rpi->firmware,
 					 RPI_FIRMWARE_GET_MAX_CLOCK_RATE,
 					 RPI_FIRMWARE_ARM_CLK_ID,
 					 &max_rate);
 	if (ret) {
 		dev_err(rpi->dev, "Failed to get %s max freq: %d\n",
 			init.name, ret);
 		return ret;
 	}

 	if (!min_rate || !max_rate) {
 		dev_err(rpi->dev, "Unexpected frequency range: min %u, max %u\n",
 			min_rate, max_rate);
 		return -EINVAL;
 	}

 	dev_info(rpi->dev, "CPU frequency range: min %u, max %u\n",
 		 min_rate, max_rate);

 	rpi->min_rate = min_rate * RPI_FIRMWARE_PLLB_ARM_DIV_RATE;
 	rpi->max_rate = max_rate * RPI_FIRMWARE_PLLB_ARM_DIV_RATE;

 	rpi->pllb.init = &init;

 	return devm_clk_hw_register(rpi->dev, &rpi->pllb);
 }

 static int raspberrypi_register_pllb_arm(struct raspberrypi_clk *rpi)
 {
 	rpi->pllb_arm = clk_hw_register_fixed_factor(rpi->dev,
 				"pllb_arm", "pllb",
 				CLK_SET_RATE_PARENT | CLK_GET_RATE_NOCACHE,
 				1, 2);
 	if (IS_ERR(rpi->pllb_arm)) {
 		dev_err(rpi->dev, "Failed to initialize pllb_arm\n");
 		return PTR_ERR(rpi->pllb_arm);
 	}

 	rpi->pllb_arm_lookup = clkdev_hw_create(rpi->pllb_arm, NULL, "cpu0");
 	if (!rpi->pllb_arm_lookup) {
 		dev_err(rpi->dev, "Failed to initialize pllb_arm_lookup\n");
 		clk_hw_unregister_fixed_factor(rpi->pllb_arm);
 		return -ENOMEM;
 	}

 	return 0;
 }

 static int raspberrypi_clk_probe(struct platform_device *pdev)
 {
 	struct device_node *firmware_node;
 	struct device *dev = &pdev->dev;
 	struct rpi_firmware *firmware;
 	struct raspberrypi_clk *rpi;
 	int ret;

 	firmware_node = of_find_compatible_node(NULL, NULL,
 					"raspberrypi,bcm2835-firmware");
 	if (!firmware_node) {
 		dev_err(dev, "Missing firmware node\n");
 		return -ENOENT;
 	}

 	firmware = rpi_firmware_get(firmware_node);
 	of_node_put(firmware_node);
 	if (!firmware)
 		return -EPROBE_DEFER;

 	rpi = devm_kzalloc(dev, sizeof(*rpi), GFP_KERNEL);
 	if (!rpi)
 		return -ENOMEM;

 	rpi->dev = dev;
 	rpi->firmware = firmware;
 	platform_set_drvdata(pdev, rpi);

 	ret = raspberrypi_register_pllb(rpi);
 	if (ret) {
 		dev_err(dev, "Failed to initialize pllb, %d\n", ret);
 		return ret;
 	}

 	ret = raspberrypi_register_pllb_arm(rpi);
 	if (ret)
 		return ret;

 	rpi->cpufreq = platform_device_register_data(dev, "raspberrypi-cpufreq",
 						     -1, NULL, 0);

 	return 0;
 }

 static int raspberrypi_clk_remove(struct platform_device *pdev)
 {
 	struct raspberrypi_clk *rpi = platform_get_drvdata(pdev);

 	platform_device_unregister(rpi->cpufreq);

 	return 0;
 }

 static struct platform_driver raspberrypi_clk_driver = {
 	.driver = {
 		.name = "raspberrypi-clk",
 	},
 	.probe          = raspberrypi_clk_probe,
 	.remove		= raspberrypi_clk_remove,
 };
 module_platform_driver(raspberrypi_clk_driver);

 MODULE_AUTHOR("Nicolas Saenz Julienne <nsaenzjulienne@suse.de>");
 MODULE_DESCRIPTION("Raspberry Pi firmware clock driver");
 MODULE_LICENSE("GPL");
 MODULE_ALIAS("platform:raspberrypi-clk");
	// 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 <nsaenzjulienne@suse.de>
	*/

	#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>

	#define RPI_FIRMWARE_ARM_CLK_ID 0x00000003

	#define RPI_FIRMWARE_STATE_ENABLE_BIT BIT(0)
	#define RPI_FIRMWARE_STATE_WAIT_BIT BIT(1)

	/*
	* Even though the firmware interface alters 'pllb' the frequencies are
	* provided as per 'pllb_arm'. We need to scale before passing them trough.
	*/
	#define RPI_FIRMWARE_PLLB_ARM_DIV_RATE 2

	#define A2W_PLL_FRAC_BITS 20

	struct raspberrypi_clk {
	struct device *dev;
	struct rpi_firmware *firmware;
	struct platform_device *cpufreq;

	unsigned long min_rate;
	unsigned long max_rate;

	struct clk_hw pllb;
	struct clk_hw *pllb_arm;
	struct clk_lookup *pllb_arm_lookup;
	};

	/*
	* 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 {
	__le32 id;
	__le32 val;
	__le32 disable_turbo;
	} __packed;

	static int raspberrypi_clock_property(struct rpi_firmware *firmware, u32 tag,
	u32 clk, u32 *val)
	{
	struct raspberrypi_firmware_prop msg = {
	.id = cpu_to_le32(clk),
	.val = cpu_to_le32(*val),
	.disable_turbo = cpu_to_le32(1),
	};
	int ret;

	ret = rpi_firmware_property(firmware, tag, &msg, sizeof(msg));
	if (ret)
	return ret;

	*val = le32_to_cpu(msg.val);

	return 0;
	}

	static int raspberrypi_fw_pll_is_on(struct clk_hw *hw)
	{
	struct raspberrypi_clk *rpi = container_of(hw, struct raspberrypi_clk,
	pllb);
	u32 val = 0;
	int ret;

	ret = raspberrypi_clock_property(rpi->firmware,
	RPI_FIRMWARE_GET_CLOCK_STATE,
	RPI_FIRMWARE_ARM_CLK_ID, &val);
	if (ret)
	return 0;

	return !!(val & RPI_FIRMWARE_STATE_ENABLE_BIT);
	}


	static unsigned long raspberrypi_fw_pll_get_rate(struct clk_hw *hw,
	unsigned long parent_rate)
	{
	struct raspberrypi_clk *rpi = container_of(hw, struct raspberrypi_clk,
	pllb);
	u32 val = 0;
	int ret;

	ret = raspberrypi_clock_property(rpi->firmware,
	RPI_FIRMWARE_GET_CLOCK_RATE,
	RPI_FIRMWARE_ARM_CLK_ID,
	&val);
	if (ret)
	return ret;

	return val * RPI_FIRMWARE_PLLB_ARM_DIV_RATE;
	}

	static int raspberrypi_fw_pll_set_rate(struct clk_hw *hw, unsigned long rate,
	unsigned long parent_rate)
	{
	struct raspberrypi_clk *rpi = container_of(hw, struct raspberrypi_clk,
	pllb);
	u32 new_rate = rate / RPI_FIRMWARE_PLLB_ARM_DIV_RATE;
	int ret;

	ret = raspberrypi_clock_property(rpi->firmware,
	RPI_FIRMWARE_SET_CLOCK_RATE,
	RPI_FIRMWARE_ARM_CLK_ID,
	&new_rate);
	if (ret)
	dev_err_ratelimited(rpi->dev, "Failed to change %s frequency: %d",
	clk_hw_get_name(hw), ret);

	return ret;
	}

	/*
	* Sadly there is no firmware rate rounding interface. We borrowed it from
	* clk-bcm2835.
	*/
	static int raspberrypi_pll_determine_rate(struct clk_hw *hw,
	struct clk_rate_request *req)
	{
	struct raspberrypi_clk *rpi = container_of(hw, struct raspberrypi_clk,
	pllb);
	u64 div, final_rate;
	u32 ndiv, fdiv;

	/* We can't use req->rate directly as it would overflow */
	final_rate = clamp(req->rate, rpi->min_rate, rpi->max_rate);

	div = (u64)final_rate << A2W_PLL_FRAC_BITS;
	do_div(div, req->best_parent_rate);

	ndiv = div >> A2W_PLL_FRAC_BITS;
	fdiv = div & ((1 << A2W_PLL_FRAC_BITS) - 1);

	final_rate = ((u64)req->best_parent_rate *
	((ndiv << A2W_PLL_FRAC_BITS) + fdiv));

	req->rate = final_rate >> A2W_PLL_FRAC_BITS;

	return 0;
	}

	static const struct clk_ops raspberrypi_firmware_pll_clk_ops = {
	.is_prepared = raspberrypi_fw_pll_is_on,
	.recalc_rate = raspberrypi_fw_pll_get_rate,
	.set_rate = raspberrypi_fw_pll_set_rate,
	.determine_rate = raspberrypi_pll_determine_rate,
	};

	static int raspberrypi_register_pllb(struct raspberrypi_clk *rpi)
	{
	u32 min_rate = 0, max_rate = 0;
	struct clk_init_data init;
	int ret;

	memset(&init, 0, sizeof(init));

	/* All of the PLLs derive from the external oscillator. */
	init.parent_names = (const char *[]){ "osc" };
	init.num_parents = 1;
	init.name = "pllb";
	init.ops = &raspberrypi_firmware_pll_clk_ops;
	init.flags = CLK_GET_RATE_NOCACHE \| CLK_IGNORE_UNUSED;

	/* Get min & max rates set by the firmware */
	ret = raspberrypi_clock_property(rpi->firmware,
	RPI_FIRMWARE_GET_MIN_CLOCK_RATE,
	RPI_FIRMWARE_ARM_CLK_ID,
	&min_rate);
	if (ret) {
	dev_err(rpi->dev, "Failed to get %s min freq: %d\n",
	init.name, ret);
	return ret;
	}

	ret = raspberrypi_clock_property(rpi->firmware,
	RPI_FIRMWARE_GET_MAX_CLOCK_RATE,
	RPI_FIRMWARE_ARM_CLK_ID,
	&max_rate);
	if (ret) {
	dev_err(rpi->dev, "Failed to get %s max freq: %d\n",
	init.name, ret);
	return ret;
	}

	if (!min_rate \|\| !max_rate) {
	dev_err(rpi->dev, "Unexpected frequency range: min %u, max %u\n",
	min_rate, max_rate);
	return -EINVAL;
	}

	dev_info(rpi->dev, "CPU frequency range: min %u, max %u\n",
	min_rate, max_rate);

	rpi->min_rate = min_rate * RPI_FIRMWARE_PLLB_ARM_DIV_RATE;
	rpi->max_rate = max_rate * RPI_FIRMWARE_PLLB_ARM_DIV_RATE;

	rpi->pllb.init = &init;

	return devm_clk_hw_register(rpi->dev, &rpi->pllb);
	}

	static int raspberrypi_register_pllb_arm(struct raspberrypi_clk *rpi)
	{
	rpi->pllb_arm = clk_hw_register_fixed_factor(rpi->dev,
	"pllb_arm", "pllb",
	CLK_SET_RATE_PARENT \| CLK_GET_RATE_NOCACHE,
	1, 2);
	if (IS_ERR(rpi->pllb_arm)) {
	dev_err(rpi->dev, "Failed to initialize pllb_arm\n");
	return PTR_ERR(rpi->pllb_arm);
	}

	rpi->pllb_arm_lookup = clkdev_hw_create(rpi->pllb_arm, NULL, "cpu0");
	if (!rpi->pllb_arm_lookup) {
	dev_err(rpi->dev, "Failed to initialize pllb_arm_lookup\n");
	clk_hw_unregister_fixed_factor(rpi->pllb_arm);
	return -ENOMEM;
	}

	return 0;
	}

	static int raspberrypi_clk_probe(struct platform_device *pdev)
	{
	struct device_node *firmware_node;
	struct device *dev = &pdev->dev;
	struct rpi_firmware *firmware;
	struct raspberrypi_clk *rpi;
	int ret;

	firmware_node = of_find_compatible_node(NULL, NULL,
	"raspberrypi,bcm2835-firmware");
	if (!firmware_node) {
	dev_err(dev, "Missing firmware node\n");
	return -ENOENT;
	}

	firmware = rpi_firmware_get(firmware_node);
	of_node_put(firmware_node);
	if (!firmware)
	return -EPROBE_DEFER;

	rpi = devm_kzalloc(dev, sizeof(*rpi), GFP_KERNEL);
	if (!rpi)
	return -ENOMEM;

	rpi->dev = dev;
	rpi->firmware = firmware;
	platform_set_drvdata(pdev, rpi);

	ret = raspberrypi_register_pllb(rpi);
	if (ret) {
	dev_err(dev, "Failed to initialize pllb, %d\n", ret);
	return ret;
	}

	ret = raspberrypi_register_pllb_arm(rpi);
	if (ret)
	return ret;

	rpi->cpufreq = platform_device_register_data(dev, "raspberrypi-cpufreq",
	-1, NULL, 0);

	return 0;
	}

	static int raspberrypi_clk_remove(struct platform_device *pdev)
	{
	struct raspberrypi_clk *rpi = platform_get_drvdata(pdev);

	platform_device_unregister(rpi->cpufreq);

	return 0;
	}

	static struct platform_driver raspberrypi_clk_driver = {
	.driver = {
	.name = "raspberrypi-clk",
	},
	.probe = raspberrypi_clk_probe,
	.remove = raspberrypi_clk_remove,
	};
	module_platform_driver(raspberrypi_clk_driver);

	MODULE_AUTHOR("Nicolas Saenz Julienne <nsaenzjulienne@suse.de>");
	MODULE_DESCRIPTION("Raspberry Pi firmware clock driver");
	MODULE_LICENSE("GPL");
	MODULE_ALIAS("platform:raspberrypi-clk");