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>

 enum rpi_firmware_clk_id {
 	RPI_FIRMWARE_EMMC_CLK_ID = 1,
 	RPI_FIRMWARE_UART_CLK_ID,
 	RPI_FIRMWARE_ARM_CLK_ID,
 	RPI_FIRMWARE_CORE_CLK_ID,
 	RPI_FIRMWARE_V3D_CLK_ID,
 	RPI_FIRMWARE_H264_CLK_ID,
 	RPI_FIRMWARE_ISP_CLK_ID,
 	RPI_FIRMWARE_SDRAM_CLK_ID,
 	RPI_FIRMWARE_PIXEL_CLK_ID,
 	RPI_FIRMWARE_PWM_CLK_ID,
 	RPI_FIRMWARE_HEVC_CLK_ID,
 	RPI_FIRMWARE_EMMC2_CLK_ID,
 	RPI_FIRMWARE_M2MC_CLK_ID,
 	RPI_FIRMWARE_PIXEL_BVB_CLK_ID,
 	RPI_FIRMWARE_NUM_CLK_ID,
 };

 static char *rpi_firmware_clk_names[] = {
 	[RPI_FIRMWARE_EMMC_CLK_ID]	= "emmc",
 	[RPI_FIRMWARE_UART_CLK_ID]	= "uart",
 	[RPI_FIRMWARE_ARM_CLK_ID]	= "arm",
 	[RPI_FIRMWARE_CORE_CLK_ID]	= "core",
 	[RPI_FIRMWARE_V3D_CLK_ID]	= "v3d",
 	[RPI_FIRMWARE_H264_CLK_ID]	= "h264",
 	[RPI_FIRMWARE_ISP_CLK_ID]	= "isp",
 	[RPI_FIRMWARE_SDRAM_CLK_ID]	= "sdram",
 	[RPI_FIRMWARE_PIXEL_CLK_ID]	= "pixel",
 	[RPI_FIRMWARE_PWM_CLK_ID]	= "pwm",
 	[RPI_FIRMWARE_HEVC_CLK_ID]	= "hevc",
 	[RPI_FIRMWARE_EMMC2_CLK_ID]	= "emmc2",
 	[RPI_FIRMWARE_M2MC_CLK_ID]	= "m2mc",
 	[RPI_FIRMWARE_PIXEL_BVB_CLK_ID]	= "pixel-bvb",
 };

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

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

 struct raspberrypi_clk_data {
 	struct clk_hw hw;

 	unsigned int id;

 	struct raspberrypi_clk *rpi;
 };

 /*
  * 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,
 				      const struct raspberrypi_clk_data *data,
 				      u32 tag, u32 *val)
 {
 	struct raspberrypi_firmware_prop msg = {
 		.id = cpu_to_le32(data->id),
 		.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_is_prepared(struct clk_hw *hw)
 {
 	struct raspberrypi_clk_data *data =
 		container_of(hw, struct raspberrypi_clk_data, hw);
 	struct raspberrypi_clk *rpi = data->rpi;
 	u32 val = 0;
 	int ret;

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

 	return !!(val & RPI_FIRMWARE_STATE_ENABLE_BIT);
 }


 static unsigned long raspberrypi_fw_get_rate(struct clk_hw *hw,
 					     unsigned long parent_rate)
 {
 	struct raspberrypi_clk_data *data =
 		container_of(hw, struct raspberrypi_clk_data, hw);
 	struct raspberrypi_clk *rpi = data->rpi;
 	u32 val = 0;
 	int ret;

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

 	return val;
 }

 static int raspberrypi_fw_set_rate(struct clk_hw *hw, unsigned long rate,
 				   unsigned long parent_rate)
 {
 	struct raspberrypi_clk_data *data =
 		container_of(hw, struct raspberrypi_clk_data, hw);
 	struct raspberrypi_clk *rpi = data->rpi;
 	u32 _rate = rate;
 	int ret;

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

 	return ret;
 }

 static int raspberrypi_fw_dumb_determine_rate(struct clk_hw *hw,
 					      struct clk_rate_request *req)
 {
 	/*
 	 * The firmware will do the rounding but that isn't part of
 	 * the interface with the firmware, so we just do our best
 	 * here.
 	 */
 	req->rate = clamp(req->rate, req->min_rate, req->max_rate);
 	return 0;
 }

 static const struct clk_ops raspberrypi_firmware_clk_ops = {
 	.is_prepared	= raspberrypi_fw_is_prepared,
 	.recalc_rate	= raspberrypi_fw_get_rate,
 	.determine_rate	= raspberrypi_fw_dumb_determine_rate,
 	.set_rate	= raspberrypi_fw_set_rate,
 };

 static struct clk_hw *raspberrypi_clk_register(struct raspberrypi_clk *rpi,
 					       unsigned int parent,
 					       unsigned int id)
 {
 	struct raspberrypi_clk_data *data;
 	struct clk_init_data init = {};
 	u32 min_rate, max_rate;
 	int ret;

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

 	init.name = devm_kasprintf(rpi->dev, GFP_KERNEL,
 				   "fw-clk-%s",
 				   rpi_firmware_clk_names[id]);
 	init.ops = &raspberrypi_firmware_clk_ops;
 	init.flags = CLK_GET_RATE_NOCACHE;

 	data->hw.init = &init;

 	ret = raspberrypi_clock_property(rpi->firmware, data,
 					 RPI_FIRMWARE_GET_MIN_CLOCK_RATE,
 					 &min_rate);
 	if (ret) {
 		dev_err(rpi->dev, "Failed to get clock %d min freq: %d",
 			id, ret);
 		return ERR_PTR(ret);
 	}

 	ret = raspberrypi_clock_property(rpi->firmware, data,
 					 RPI_FIRMWARE_GET_MAX_CLOCK_RATE,
 					 &max_rate);
 	if (ret) {
 		dev_err(rpi->dev, "Failed to get clock %d max freq: %d\n",
 			id, ret);
 		return ERR_PTR(ret);
 	}

 	ret = devm_clk_hw_register(rpi->dev, &data->hw);
 	if (ret)
 		return ERR_PTR(ret);

 	clk_hw_set_rate_range(&data->hw, min_rate, max_rate);

 	if (id == RPI_FIRMWARE_ARM_CLK_ID) {
 		ret = devm_clk_hw_register_clkdev(rpi->dev, &data->hw,
 						  NULL, "cpu0");
 		if (ret) {
 			dev_err(rpi->dev, "Failed to initialize clkdev\n");
 			return ERR_PTR(ret);
 		}
 	}

 	return &data->hw;
 }

 struct rpi_firmware_get_clocks_response {
 	u32 parent;
 	u32 id;
 };

 static int raspberrypi_discover_clocks(struct raspberrypi_clk *rpi,
 				       struct clk_hw_onecell_data *data)
 {
 	struct rpi_firmware_get_clocks_response *clks;
 	int ret;

 	clks = devm_kcalloc(rpi->dev,
 			    sizeof(*clks), RPI_FIRMWARE_NUM_CLK_ID,
 			    GFP_KERNEL);
 	if (!clks)
 		return -ENOMEM;

 	ret = rpi_firmware_property(rpi->firmware, RPI_FIRMWARE_GET_CLOCKS,
 				    clks,
 				    sizeof(*clks) * RPI_FIRMWARE_NUM_CLK_ID);
 	if (ret)
 		return ret;

 	while (clks->id) {
 		struct clk_hw *hw;

 		switch (clks->id) {
 		case RPI_FIRMWARE_ARM_CLK_ID:
 		case RPI_FIRMWARE_CORE_CLK_ID:
 		case RPI_FIRMWARE_M2MC_CLK_ID:
 		case RPI_FIRMWARE_V3D_CLK_ID:
 		case RPI_FIRMWARE_PIXEL_BVB_CLK_ID:
 			hw = raspberrypi_clk_register(rpi, clks->parent,
 						      clks->id);
 			if (IS_ERR(hw))
 				return PTR_ERR(hw);

 			data->hws[clks->id] = hw;
 			data->num = clks->id + 1;
 			fallthrough;

 		default:
 			clks++;
 			break;
 		}
 	}

 	return 0;
 }

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

 	/*
 	 * We can be probed either through the an old-fashioned
 	 * platform device registration or through a DT node that is a
 	 * child of the firmware node. Handle both cases.
 	 */
 	if (dev->of_node)
 		firmware_node = of_get_parent(dev->of_node);
 	else
 		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);

 	clk_data = devm_kzalloc(dev, struct_size(clk_data, hws,
 						 RPI_FIRMWARE_NUM_CLK_ID),
 				GFP_KERNEL);
 	if (!clk_data)
 		return -ENOMEM;

 	ret = raspberrypi_discover_clocks(rpi, clk_data);
 	if (ret)
 		return ret;

 	ret = devm_of_clk_add_hw_provider(dev, of_clk_hw_onecell_get,
 					  clk_data);
 	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 const struct of_device_id raspberrypi_clk_match[] = {
 	{ .compatible = "raspberrypi,firmware-clocks" },
 	{ },
 };
 MODULE_DEVICE_TABLE(of, raspberrypi_clk_match);

 static struct platform_driver raspberrypi_clk_driver = {
 	.driver = {
 		.name = "raspberrypi-clk",
 		.of_match_table = raspberrypi_clk_match,
 	},
 	.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>

	enum rpi_firmware_clk_id {
	RPI_FIRMWARE_EMMC_CLK_ID = 1,
	RPI_FIRMWARE_UART_CLK_ID,
	RPI_FIRMWARE_ARM_CLK_ID,
	RPI_FIRMWARE_CORE_CLK_ID,
	RPI_FIRMWARE_V3D_CLK_ID,
	RPI_FIRMWARE_H264_CLK_ID,
	RPI_FIRMWARE_ISP_CLK_ID,
	RPI_FIRMWARE_SDRAM_CLK_ID,
	RPI_FIRMWARE_PIXEL_CLK_ID,
	RPI_FIRMWARE_PWM_CLK_ID,
	RPI_FIRMWARE_HEVC_CLK_ID,
	RPI_FIRMWARE_EMMC2_CLK_ID,
	RPI_FIRMWARE_M2MC_CLK_ID,
	RPI_FIRMWARE_PIXEL_BVB_CLK_ID,
	RPI_FIRMWARE_NUM_CLK_ID,
	};

	static char *rpi_firmware_clk_names[] = {
	[RPI_FIRMWARE_EMMC_CLK_ID] = "emmc",
	[RPI_FIRMWARE_UART_CLK_ID] = "uart",
	[RPI_FIRMWARE_ARM_CLK_ID] = "arm",
	[RPI_FIRMWARE_CORE_CLK_ID] = "core",
	[RPI_FIRMWARE_V3D_CLK_ID] = "v3d",
	[RPI_FIRMWARE_H264_CLK_ID] = "h264",
	[RPI_FIRMWARE_ISP_CLK_ID] = "isp",
	[RPI_FIRMWARE_SDRAM_CLK_ID] = "sdram",
	[RPI_FIRMWARE_PIXEL_CLK_ID] = "pixel",
	[RPI_FIRMWARE_PWM_CLK_ID] = "pwm",
	[RPI_FIRMWARE_HEVC_CLK_ID] = "hevc",
	[RPI_FIRMWARE_EMMC2_CLK_ID] = "emmc2",
	[RPI_FIRMWARE_M2MC_CLK_ID] = "m2mc",
	[RPI_FIRMWARE_PIXEL_BVB_CLK_ID] = "pixel-bvb",
	};

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

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

	struct raspberrypi_clk_data {
	struct clk_hw hw;

	unsigned int id;

	struct raspberrypi_clk *rpi;
	};

	/*
	* 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,
	const struct raspberrypi_clk_data *data,
	u32 tag, u32 *val)
	{
	struct raspberrypi_firmware_prop msg = {
	.id = cpu_to_le32(data->id),
	.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_is_prepared(struct clk_hw *hw)
	{
	struct raspberrypi_clk_data *data =
	container_of(hw, struct raspberrypi_clk_data, hw);
	struct raspberrypi_clk *rpi = data->rpi;
	u32 val = 0;
	int ret;

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

	return !!(val & RPI_FIRMWARE_STATE_ENABLE_BIT);
	}


	static unsigned long raspberrypi_fw_get_rate(struct clk_hw *hw,
	unsigned long parent_rate)
	{
	struct raspberrypi_clk_data *data =
	container_of(hw, struct raspberrypi_clk_data, hw);
	struct raspberrypi_clk *rpi = data->rpi;
	u32 val = 0;
	int ret;

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

	return val;
	}

	static int raspberrypi_fw_set_rate(struct clk_hw *hw, unsigned long rate,
	unsigned long parent_rate)
	{
	struct raspberrypi_clk_data *data =
	container_of(hw, struct raspberrypi_clk_data, hw);
	struct raspberrypi_clk *rpi = data->rpi;
	u32 _rate = rate;
	int ret;

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

	return ret;
	}

	static int raspberrypi_fw_dumb_determine_rate(struct clk_hw *hw,
	struct clk_rate_request *req)
	{
	/*
	* The firmware will do the rounding but that isn't part of
	* the interface with the firmware, so we just do our best
	* here.
	*/
	req->rate = clamp(req->rate, req->min_rate, req->max_rate);
	return 0;
	}

	static const struct clk_ops raspberrypi_firmware_clk_ops = {
	.is_prepared = raspberrypi_fw_is_prepared,
	.recalc_rate = raspberrypi_fw_get_rate,
	.determine_rate = raspberrypi_fw_dumb_determine_rate,
	.set_rate = raspberrypi_fw_set_rate,
	};

	static struct clk_hw raspberrypi_clk_register(struct raspberrypi_clk rpi,
	unsigned int parent,
	unsigned int id)
	{
	struct raspberrypi_clk_data *data;
	struct clk_init_data init = {};
	u32 min_rate, max_rate;
	int ret;

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

	init.name = devm_kasprintf(rpi->dev, GFP_KERNEL,
	"fw-clk-%s",
	rpi_firmware_clk_names[id]);
	init.ops = &raspberrypi_firmware_clk_ops;
	init.flags = CLK_GET_RATE_NOCACHE;

	data->hw.init = &init;

	ret = raspberrypi_clock_property(rpi->firmware, data,
	RPI_FIRMWARE_GET_MIN_CLOCK_RATE,
	&min_rate);
	if (ret) {
	dev_err(rpi->dev, "Failed to get clock %d min freq: %d",
	id, ret);
	return ERR_PTR(ret);
	}

	ret = raspberrypi_clock_property(rpi->firmware, data,
	RPI_FIRMWARE_GET_MAX_CLOCK_RATE,
	&max_rate);
	if (ret) {
	dev_err(rpi->dev, "Failed to get clock %d max freq: %d\n",
	id, ret);
	return ERR_PTR(ret);
	}

	ret = devm_clk_hw_register(rpi->dev, &data->hw);
	if (ret)
	return ERR_PTR(ret);

	clk_hw_set_rate_range(&data->hw, min_rate, max_rate);

	if (id == RPI_FIRMWARE_ARM_CLK_ID) {
	ret = devm_clk_hw_register_clkdev(rpi->dev, &data->hw,
	NULL, "cpu0");
	if (ret) {
	dev_err(rpi->dev, "Failed to initialize clkdev\n");
	return ERR_PTR(ret);
	}
	}

	return &data->hw;
	}

	struct rpi_firmware_get_clocks_response {
	u32 parent;
	u32 id;
	};

	static int raspberrypi_discover_clocks(struct raspberrypi_clk *rpi,
	struct clk_hw_onecell_data *data)
	{
	struct rpi_firmware_get_clocks_response *clks;
	int ret;

	clks = devm_kcalloc(rpi->dev,
	sizeof(*clks), RPI_FIRMWARE_NUM_CLK_ID,
	GFP_KERNEL);
	if (!clks)
	return -ENOMEM;

	ret = rpi_firmware_property(rpi->firmware, RPI_FIRMWARE_GET_CLOCKS,
	clks,
	sizeof(clks) RPI_FIRMWARE_NUM_CLK_ID);
	if (ret)
	return ret;

	while (clks->id) {
	struct clk_hw *hw;

	switch (clks->id) {
	case RPI_FIRMWARE_ARM_CLK_ID:
	case RPI_FIRMWARE_CORE_CLK_ID:
	case RPI_FIRMWARE_M2MC_CLK_ID:
	case RPI_FIRMWARE_V3D_CLK_ID:
	case RPI_FIRMWARE_PIXEL_BVB_CLK_ID:
	hw = raspberrypi_clk_register(rpi, clks->parent,
	clks->id);
	if (IS_ERR(hw))
	return PTR_ERR(hw);

	data->hws[clks->id] = hw;
	data->num = clks->id + 1;
	fallthrough;

	default:
	clks++;
	break;
	}
	}

	return 0;
	}

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

	/*
	* We can be probed either through the an old-fashioned
	* platform device registration or through a DT node that is a
	* child of the firmware node. Handle both cases.
	*/
	if (dev->of_node)
	firmware_node = of_get_parent(dev->of_node);
	else
	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);

	clk_data = devm_kzalloc(dev, struct_size(clk_data, hws,
	RPI_FIRMWARE_NUM_CLK_ID),
	GFP_KERNEL);
	if (!clk_data)
	return -ENOMEM;

	ret = raspberrypi_discover_clocks(rpi, clk_data);
	if (ret)
	return ret;

	ret = devm_of_clk_add_hw_provider(dev, of_clk_hw_onecell_get,
	clk_data);
	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 const struct of_device_id raspberrypi_clk_match[] = {
	{ .compatible = "raspberrypi,firmware-clocks" },
	{ },
	};
	MODULE_DEVICE_TABLE(of, raspberrypi_clk_match);

	static struct platform_driver raspberrypi_clk_driver = {
	.driver = {
	.name = "raspberrypi-clk",
	.of_match_table = raspberrypi_clk_match,
	},
	.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");