diff options
| -rw-r--r-- | drivers/clk/bcm/Kconfig | 7 | ||||
| -rw-r--r-- | drivers/clk/bcm/Makefile | 1 | ||||
| -rw-r--r-- | drivers/clk/bcm/clk-raspberrypi.c | 300 |
3 files changed, 308 insertions, 0 deletions
diff --git a/drivers/clk/bcm/Kconfig b/drivers/clk/bcm/Kconfig index 0eb281d597fc..e5497e995cfb 100644 --- a/drivers/clk/bcm/Kconfig +++ b/drivers/clk/bcm/Kconfig @@ -72,3 +72,10 @@ config CLK_BCM_SR default ARCH_BCM_IPROC help Enable common clock framework support for the Broadcom Stingray SoC + +config CLK_RASPBERRYPI + tristate "Raspberry Pi firmware based clock support" + depends on RASPBERRYPI_FIRMWARE || (COMPILE_TEST && !RASPBERRYPI_FIRMWARE) + help + Enable common clock framework support for Raspberry Pi's firmware + dependent clocks diff --git a/drivers/clk/bcm/Makefile b/drivers/clk/bcm/Makefile index e924f25bc6c8..004e9526d6f6 100644 --- a/drivers/clk/bcm/Makefile +++ b/drivers/clk/bcm/Makefile @@ -7,6 +7,7 @@ obj-$(CONFIG_CLK_BCM_KONA) += clk-bcm21664.o obj-$(CONFIG_COMMON_CLK_IPROC) += clk-iproc-armpll.o clk-iproc-pll.o clk-iproc-asiu.o obj-$(CONFIG_CLK_BCM2835) += clk-bcm2835.o obj-$(CONFIG_CLK_BCM2835) += clk-bcm2835-aux.o +obj-$(CONFIG_CLK_RASPBERRYPI) += clk-raspberrypi.o obj-$(CONFIG_ARCH_BCM_53573) += clk-bcm53573-ilp.o obj-$(CONFIG_CLK_BCM_CYGNUS) += clk-cygnus.o obj-$(CONFIG_CLK_BCM_HR2) += clk-hr2.o diff --git a/drivers/clk/bcm/clk-raspberrypi.c b/drivers/clk/bcm/clk-raspberrypi.c new file mode 100644 index 000000000000..fef1f7caee4f --- /dev/null +++ b/drivers/clk/bcm/clk-raspberrypi.c @@ -0,0 +1,300 @@ +// 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; + + 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; + + 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; + + return 0; +} + +static struct platform_driver raspberrypi_clk_driver = { + .driver = { + .name = "raspberrypi-clk", + }, + .probe = raspberrypi_clk_probe, +}; +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"); |