diff options
Diffstat (limited to 'drivers/clk/bcm/clk-raspberrypi.c')
| -rw-r--r-- | drivers/clk/bcm/clk-raspberrypi.c | 384 |
1 files changed, 384 insertions, 0 deletions
diff --git a/drivers/clk/bcm/clk-raspberrypi.c b/drivers/clk/bcm/clk-raspberrypi.c new file mode 100644 index 000000000..969227e2d --- /dev/null +++ b/drivers/clk/bcm/clk-raspberrypi.c @@ -0,0 +1,384 @@ +// 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 0; + + 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\n", + 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\n", + 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; + + /* + * The firmware doesn't guarantee that the last element of + * RPI_FIRMWARE_GET_CLOCKS is zeroed. So allocate an additional + * zero element as sentinel. + */ + clks = devm_kcalloc(rpi->dev, + RPI_FIRMWARE_NUM_CLK_ID + 1, sizeof(*clks), + 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"); |