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380 lines
9.5 KiB
380 lines
9.5 KiB
// SPDX-License-Identifier: GPL-2.0+ |
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/* |
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* Raspberry Pi driver for firmware controlled clocks |
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* |
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* Even though clk-bcm2835 provides an interface to the hardware registers for |
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* the system clocks we've had to factor out 'pllb' as the firmware 'owns' it. |
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* We're not allowed to change it directly as we might race with the |
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* over-temperature and under-voltage protections provided by the firmware. |
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* |
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* Copyright (C) 2019 Nicolas Saenz Julienne <[email protected]> |
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*/ |
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#include <linux/clkdev.h> |
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#include <linux/clk-provider.h> |
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#include <linux/io.h> |
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#include <linux/module.h> |
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#include <linux/platform_device.h> |
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#include <soc/bcm2835/raspberrypi-firmware.h> |
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enum rpi_firmware_clk_id { |
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RPI_FIRMWARE_EMMC_CLK_ID = 1, |
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RPI_FIRMWARE_UART_CLK_ID, |
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RPI_FIRMWARE_ARM_CLK_ID, |
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RPI_FIRMWARE_CORE_CLK_ID, |
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RPI_FIRMWARE_V3D_CLK_ID, |
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RPI_FIRMWARE_H264_CLK_ID, |
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RPI_FIRMWARE_ISP_CLK_ID, |
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RPI_FIRMWARE_SDRAM_CLK_ID, |
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RPI_FIRMWARE_PIXEL_CLK_ID, |
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RPI_FIRMWARE_PWM_CLK_ID, |
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RPI_FIRMWARE_HEVC_CLK_ID, |
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RPI_FIRMWARE_EMMC2_CLK_ID, |
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RPI_FIRMWARE_M2MC_CLK_ID, |
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RPI_FIRMWARE_PIXEL_BVB_CLK_ID, |
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RPI_FIRMWARE_NUM_CLK_ID, |
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}; |
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static char *rpi_firmware_clk_names[] = { |
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[RPI_FIRMWARE_EMMC_CLK_ID] = "emmc", |
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[RPI_FIRMWARE_UART_CLK_ID] = "uart", |
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[RPI_FIRMWARE_ARM_CLK_ID] = "arm", |
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[RPI_FIRMWARE_CORE_CLK_ID] = "core", |
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[RPI_FIRMWARE_V3D_CLK_ID] = "v3d", |
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[RPI_FIRMWARE_H264_CLK_ID] = "h264", |
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[RPI_FIRMWARE_ISP_CLK_ID] = "isp", |
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[RPI_FIRMWARE_SDRAM_CLK_ID] = "sdram", |
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[RPI_FIRMWARE_PIXEL_CLK_ID] = "pixel", |
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[RPI_FIRMWARE_PWM_CLK_ID] = "pwm", |
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[RPI_FIRMWARE_HEVC_CLK_ID] = "hevc", |
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[RPI_FIRMWARE_EMMC2_CLK_ID] = "emmc2", |
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[RPI_FIRMWARE_M2MC_CLK_ID] = "m2mc", |
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[RPI_FIRMWARE_PIXEL_BVB_CLK_ID] = "pixel-bvb", |
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}; |
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#define RPI_FIRMWARE_STATE_ENABLE_BIT BIT(0) |
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#define RPI_FIRMWARE_STATE_WAIT_BIT BIT(1) |
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struct raspberrypi_clk { |
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struct device *dev; |
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struct rpi_firmware *firmware; |
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struct platform_device *cpufreq; |
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}; |
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struct raspberrypi_clk_data { |
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struct clk_hw hw; |
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unsigned int id; |
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struct raspberrypi_clk *rpi; |
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}; |
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/* |
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* Structure of the message passed to Raspberry Pi's firmware in order to |
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* change clock rates. The 'disable_turbo' option is only available to the ARM |
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* clock (pllb) which we enable by default as turbo mode will alter multiple |
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* clocks at once. |
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* |
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* Even though we're able to access the clock registers directly we're bound to |
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* use the firmware interface as the firmware ultimately takes care of |
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* mitigating overheating/undervoltage situations and we would be changing |
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* frequencies behind his back. |
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* |
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* For more information on the firmware interface check: |
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* https://github.com/raspberrypi/firmware/wiki/Mailbox-property-interface |
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*/ |
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struct raspberrypi_firmware_prop { |
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__le32 id; |
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__le32 val; |
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__le32 disable_turbo; |
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} __packed; |
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static int raspberrypi_clock_property(struct rpi_firmware *firmware, |
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const struct raspberrypi_clk_data *data, |
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u32 tag, u32 *val) |
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{ |
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struct raspberrypi_firmware_prop msg = { |
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.id = cpu_to_le32(data->id), |
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.val = cpu_to_le32(*val), |
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.disable_turbo = cpu_to_le32(0), |
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}; |
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int ret; |
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ret = rpi_firmware_property(firmware, tag, &msg, sizeof(msg)); |
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if (ret) |
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return ret; |
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*val = le32_to_cpu(msg.val); |
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return 0; |
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} |
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static int raspberrypi_fw_is_prepared(struct clk_hw *hw) |
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{ |
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struct raspberrypi_clk_data *data = |
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container_of(hw, struct raspberrypi_clk_data, hw); |
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struct raspberrypi_clk *rpi = data->rpi; |
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u32 val = 0; |
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int ret; |
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ret = raspberrypi_clock_property(rpi->firmware, data, |
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RPI_FIRMWARE_GET_CLOCK_STATE, &val); |
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if (ret) |
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return 0; |
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return !!(val & RPI_FIRMWARE_STATE_ENABLE_BIT); |
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} |
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static unsigned long raspberrypi_fw_get_rate(struct clk_hw *hw, |
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unsigned long parent_rate) |
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{ |
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struct raspberrypi_clk_data *data = |
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container_of(hw, struct raspberrypi_clk_data, hw); |
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struct raspberrypi_clk *rpi = data->rpi; |
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u32 val = 0; |
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int ret; |
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ret = raspberrypi_clock_property(rpi->firmware, data, |
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RPI_FIRMWARE_GET_CLOCK_RATE, &val); |
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if (ret) |
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return ret; |
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return val; |
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} |
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static int raspberrypi_fw_set_rate(struct clk_hw *hw, unsigned long rate, |
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unsigned long parent_rate) |
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{ |
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struct raspberrypi_clk_data *data = |
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container_of(hw, struct raspberrypi_clk_data, hw); |
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struct raspberrypi_clk *rpi = data->rpi; |
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u32 _rate = rate; |
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int ret; |
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ret = raspberrypi_clock_property(rpi->firmware, data, |
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RPI_FIRMWARE_SET_CLOCK_RATE, &_rate); |
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if (ret) |
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dev_err_ratelimited(rpi->dev, "Failed to change %s frequency: %d", |
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clk_hw_get_name(hw), ret); |
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return ret; |
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} |
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static int raspberrypi_fw_dumb_determine_rate(struct clk_hw *hw, |
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struct clk_rate_request *req) |
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{ |
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/* |
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* The firmware will do the rounding but that isn't part of |
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* the interface with the firmware, so we just do our best |
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* here. |
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*/ |
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req->rate = clamp(req->rate, req->min_rate, req->max_rate); |
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return 0; |
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} |
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static const struct clk_ops raspberrypi_firmware_clk_ops = { |
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.is_prepared = raspberrypi_fw_is_prepared, |
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.recalc_rate = raspberrypi_fw_get_rate, |
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.determine_rate = raspberrypi_fw_dumb_determine_rate, |
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.set_rate = raspberrypi_fw_set_rate, |
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}; |
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static struct clk_hw *raspberrypi_clk_register(struct raspberrypi_clk *rpi, |
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unsigned int parent, |
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unsigned int id) |
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{ |
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struct raspberrypi_clk_data *data; |
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struct clk_init_data init = {}; |
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u32 min_rate, max_rate; |
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int ret; |
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data = devm_kzalloc(rpi->dev, sizeof(*data), GFP_KERNEL); |
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if (!data) |
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return ERR_PTR(-ENOMEM); |
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data->rpi = rpi; |
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data->id = id; |
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init.name = devm_kasprintf(rpi->dev, GFP_KERNEL, |
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"fw-clk-%s", |
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rpi_firmware_clk_names[id]); |
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init.ops = &raspberrypi_firmware_clk_ops; |
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init.flags = CLK_GET_RATE_NOCACHE; |
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data->hw.init = &init; |
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ret = raspberrypi_clock_property(rpi->firmware, data, |
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RPI_FIRMWARE_GET_MIN_CLOCK_RATE, |
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&min_rate); |
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if (ret) { |
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dev_err(rpi->dev, "Failed to get clock %d min freq: %d", |
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id, ret); |
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return ERR_PTR(ret); |
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} |
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ret = raspberrypi_clock_property(rpi->firmware, data, |
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RPI_FIRMWARE_GET_MAX_CLOCK_RATE, |
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&max_rate); |
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if (ret) { |
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dev_err(rpi->dev, "Failed to get clock %d max freq: %d\n", |
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id, ret); |
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return ERR_PTR(ret); |
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} |
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ret = devm_clk_hw_register(rpi->dev, &data->hw); |
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if (ret) |
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return ERR_PTR(ret); |
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clk_hw_set_rate_range(&data->hw, min_rate, max_rate); |
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if (id == RPI_FIRMWARE_ARM_CLK_ID) { |
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ret = devm_clk_hw_register_clkdev(rpi->dev, &data->hw, |
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NULL, "cpu0"); |
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if (ret) { |
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dev_err(rpi->dev, "Failed to initialize clkdev\n"); |
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return ERR_PTR(ret); |
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} |
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} |
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return &data->hw; |
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} |
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struct rpi_firmware_get_clocks_response { |
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u32 parent; |
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u32 id; |
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}; |
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static int raspberrypi_discover_clocks(struct raspberrypi_clk *rpi, |
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struct clk_hw_onecell_data *data) |
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{ |
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struct rpi_firmware_get_clocks_response *clks; |
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int ret; |
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clks = devm_kcalloc(rpi->dev, |
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sizeof(*clks), RPI_FIRMWARE_NUM_CLK_ID, |
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GFP_KERNEL); |
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if (!clks) |
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return -ENOMEM; |
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ret = rpi_firmware_property(rpi->firmware, RPI_FIRMWARE_GET_CLOCKS, |
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clks, |
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sizeof(*clks) * RPI_FIRMWARE_NUM_CLK_ID); |
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if (ret) |
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return ret; |
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while (clks->id) { |
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struct clk_hw *hw; |
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switch (clks->id) { |
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case RPI_FIRMWARE_ARM_CLK_ID: |
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case RPI_FIRMWARE_CORE_CLK_ID: |
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case RPI_FIRMWARE_M2MC_CLK_ID: |
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case RPI_FIRMWARE_V3D_CLK_ID: |
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case RPI_FIRMWARE_HEVC_CLK_ID: |
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case RPI_FIRMWARE_PIXEL_BVB_CLK_ID: |
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hw = raspberrypi_clk_register(rpi, clks->parent, |
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clks->id); |
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if (IS_ERR(hw)) |
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return PTR_ERR(hw); |
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data->hws[clks->id] = hw; |
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data->num = clks->id + 1; |
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fallthrough; |
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default: |
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clks++; |
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break; |
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} |
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} |
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return 0; |
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} |
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static int raspberrypi_clk_probe(struct platform_device *pdev) |
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{ |
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struct clk_hw_onecell_data *clk_data; |
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struct device_node *firmware_node; |
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struct device *dev = &pdev->dev; |
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struct rpi_firmware *firmware; |
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struct raspberrypi_clk *rpi; |
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int ret; |
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/* |
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* We can be probed either through the an old-fashioned |
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* platform device registration or through a DT node that is a |
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* child of the firmware node. Handle both cases. |
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*/ |
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if (dev->of_node) |
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firmware_node = of_get_parent(dev->of_node); |
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else |
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firmware_node = of_find_compatible_node(NULL, NULL, |
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"raspberrypi,bcm2835-firmware"); |
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if (!firmware_node) { |
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dev_err(dev, "Missing firmware node\n"); |
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return -ENOENT; |
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} |
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firmware = rpi_firmware_get(firmware_node); |
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of_node_put(firmware_node); |
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if (!firmware) |
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return -EPROBE_DEFER; |
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rpi = devm_kzalloc(dev, sizeof(*rpi), GFP_KERNEL); |
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if (!rpi) |
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return -ENOMEM; |
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rpi->dev = dev; |
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rpi->firmware = firmware; |
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platform_set_drvdata(pdev, rpi); |
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clk_data = devm_kzalloc(dev, struct_size(clk_data, hws, |
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RPI_FIRMWARE_NUM_CLK_ID), |
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GFP_KERNEL); |
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if (!clk_data) |
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return -ENOMEM; |
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ret = raspberrypi_discover_clocks(rpi, clk_data); |
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if (ret) |
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return ret; |
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ret = devm_of_clk_add_hw_provider(dev, of_clk_hw_onecell_get, |
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clk_data); |
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if (ret) |
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return ret; |
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rpi->cpufreq = platform_device_register_data(dev, "raspberrypi-cpufreq", |
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-1, NULL, 0); |
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return 0; |
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} |
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static int raspberrypi_clk_remove(struct platform_device *pdev) |
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{ |
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struct raspberrypi_clk *rpi = platform_get_drvdata(pdev); |
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platform_device_unregister(rpi->cpufreq); |
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return 0; |
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} |
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static const struct of_device_id raspberrypi_clk_match[] = { |
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{ .compatible = "raspberrypi,firmware-clocks" }, |
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{ }, |
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}; |
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MODULE_DEVICE_TABLE(of, raspberrypi_clk_match); |
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static struct platform_driver raspberrypi_clk_driver = { |
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.driver = { |
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.name = "raspberrypi-clk", |
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.of_match_table = raspberrypi_clk_match, |
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}, |
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.probe = raspberrypi_clk_probe, |
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.remove = raspberrypi_clk_remove, |
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}; |
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module_platform_driver(raspberrypi_clk_driver); |
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MODULE_AUTHOR("Nicolas Saenz Julienne <[email protected]>"); |
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MODULE_DESCRIPTION("Raspberry Pi firmware clock driver"); |
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MODULE_LICENSE("GPL"); |
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MODULE_ALIAS("platform:raspberrypi-clk");
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