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authorNicolas Saenz Julienne <nsaenzjulienne@suse.de>2021-01-18 13:32:44 +0100
committerNicolas Saenz Julienne <nsaenzjulienne@suse.de>2021-03-22 17:59:52 +0100
commit79caa362eab6569297210eda375d6ea358a81161 (patch)
tree46d19f76d7c743728e0202bc6a11701a98b6a0c3 /drivers/pwm
parenta953e68ef2df657d8b65e16370e5808ec5819f23 (diff)
pwm: Add Raspberry Pi Firmware based PWM bus
Adds support to control the PWM bus available in official Raspberry Pi PoE HAT. Only RPi's co-processor has access to it, so commands have to be sent through RPi's firmware mailbox interface. Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de> Reviewed-by: Uwe Kleine-K├Ânig <u.kleine-koenig@pengutronix.de> Acked-by: Thierry Reding <thierry.reding@gmail.com>
Diffstat (limited to 'drivers/pwm')
-rw-r--r--drivers/pwm/Kconfig9
-rw-r--r--drivers/pwm/Makefile1
-rw-r--r--drivers/pwm/pwm-raspberrypi-poe.c206
3 files changed, 216 insertions, 0 deletions
diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index 9a4f66ae8070..43d9f1884cd3 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -423,6 +423,15 @@ config PWM_PXA
To compile this driver as a module, choose M here: the module
will be called pwm-pxa.
+config PWM_RASPBERRYPI_POE
+ tristate "Raspberry Pi Firwmware PoE Hat PWM support"
+ # Make sure not 'y' when RASPBERRYPI_FIRMWARE is 'm'. This can only
+ # happen when COMPILE_TEST=y, hence the added !RASPBERRYPI_FIRMWARE.
+ depends on RASPBERRYPI_FIRMWARE || (COMPILE_TEST && !RASPBERRYPI_FIRMWARE)
+ help
+ Enable Raspberry Pi firmware controller PWM bus used to control the
+ official RPI PoE hat
+
config PWM_RCAR
tristate "Renesas R-Car PWM support"
depends on ARCH_RENESAS || COMPILE_TEST
diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
index 6374d3b1d6f3..211db810c439 100644
--- a/drivers/pwm/Makefile
+++ b/drivers/pwm/Makefile
@@ -38,6 +38,7 @@ obj-$(CONFIG_PWM_MXS) += pwm-mxs.o
obj-$(CONFIG_PWM_OMAP_DMTIMER) += pwm-omap-dmtimer.o
obj-$(CONFIG_PWM_PCA9685) += pwm-pca9685.o
obj-$(CONFIG_PWM_PXA) += pwm-pxa.o
+obj-$(CONFIG_PWM_RASPBERRYPI_POE) += pwm-raspberrypi-poe.o
obj-$(CONFIG_PWM_RCAR) += pwm-rcar.o
obj-$(CONFIG_PWM_RENESAS_TPU) += pwm-renesas-tpu.o
obj-$(CONFIG_PWM_ROCKCHIP) += pwm-rockchip.o
diff --git a/drivers/pwm/pwm-raspberrypi-poe.c b/drivers/pwm/pwm-raspberrypi-poe.c
new file mode 100644
index 000000000000..043fc32e8be8
--- /dev/null
+++ b/drivers/pwm/pwm-raspberrypi-poe.c
@@ -0,0 +1,206 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2021 Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
+ * For more information on Raspberry Pi's PoE hat see:
+ * https://www.raspberrypi.org/products/poe-hat/
+ *
+ * Limitations:
+ * - No disable bit, so a disabled PWM is simulated by duty_cycle 0
+ * - Only normal polarity
+ * - Fixed 12.5 kHz period
+ *
+ * The current period is completed when HW is reconfigured.
+ */
+
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/pwm.h>
+
+#include <soc/bcm2835/raspberrypi-firmware.h>
+#include <dt-bindings/pwm/raspberrypi,firmware-poe-pwm.h>
+
+#define RPI_PWM_MAX_DUTY 255
+#define RPI_PWM_PERIOD_NS 80000 /* 12.5 kHz */
+
+#define RPI_PWM_CUR_DUTY_REG 0x0
+
+struct raspberrypi_pwm {
+ struct rpi_firmware *firmware;
+ struct pwm_chip chip;
+ unsigned int duty_cycle;
+};
+
+struct raspberrypi_pwm_prop {
+ __le32 reg;
+ __le32 val;
+ __le32 ret;
+} __packed;
+
+static inline
+struct raspberrypi_pwm *raspberrypi_pwm_from_chip(struct pwm_chip *chip)
+{
+ return container_of(chip, struct raspberrypi_pwm, chip);
+}
+
+static int raspberrypi_pwm_set_property(struct rpi_firmware *firmware,
+ u32 reg, u32 val)
+{
+ struct raspberrypi_pwm_prop msg = {
+ .reg = cpu_to_le32(reg),
+ .val = cpu_to_le32(val),
+ };
+ int ret;
+
+ ret = rpi_firmware_property(firmware, RPI_FIRMWARE_SET_POE_HAT_VAL,
+ &msg, sizeof(msg));
+ if (ret)
+ return ret;
+ if (msg.ret)
+ return -EIO;
+
+ return 0;
+}
+
+static int raspberrypi_pwm_get_property(struct rpi_firmware *firmware,
+ u32 reg, u32 *val)
+{
+ struct raspberrypi_pwm_prop msg = {
+ .reg = reg
+ };
+ int ret;
+
+ ret = rpi_firmware_property(firmware, RPI_FIRMWARE_GET_POE_HAT_VAL,
+ &msg, sizeof(msg));
+ if (ret)
+ return ret;
+ if (msg.ret)
+ return -EIO;
+
+ *val = le32_to_cpu(msg.val);
+
+ return 0;
+}
+
+static void raspberrypi_pwm_get_state(struct pwm_chip *chip,
+ struct pwm_device *pwm,
+ struct pwm_state *state)
+{
+ struct raspberrypi_pwm *rpipwm = raspberrypi_pwm_from_chip(chip);
+
+ state->period = RPI_PWM_PERIOD_NS;
+ state->duty_cycle = DIV_ROUND_UP(rpipwm->duty_cycle * RPI_PWM_PERIOD_NS,
+ RPI_PWM_MAX_DUTY);
+ state->enabled = !!(rpipwm->duty_cycle);
+ state->polarity = PWM_POLARITY_NORMAL;
+}
+
+static int raspberrypi_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
+ const struct pwm_state *state)
+{
+ struct raspberrypi_pwm *rpipwm = raspberrypi_pwm_from_chip(chip);
+ unsigned int duty_cycle;
+ int ret;
+
+ if (state->period < RPI_PWM_PERIOD_NS ||
+ state->polarity != PWM_POLARITY_NORMAL)
+ return -EINVAL;
+
+ if (!state->enabled)
+ duty_cycle = 0;
+ else if (state->duty_cycle < RPI_PWM_PERIOD_NS)
+ duty_cycle = DIV_ROUND_DOWN_ULL(state->duty_cycle * RPI_PWM_MAX_DUTY,
+ RPI_PWM_PERIOD_NS);
+ else
+ duty_cycle = RPI_PWM_MAX_DUTY;
+
+ if (duty_cycle == rpipwm->duty_cycle)
+ return 0;
+
+ ret = raspberrypi_pwm_set_property(rpipwm->firmware, RPI_PWM_CUR_DUTY_REG,
+ duty_cycle);
+ if (ret) {
+ dev_err(chip->dev, "Failed to set duty cycle: %pe\n",
+ ERR_PTR(ret));
+ return ret;
+ }
+
+ rpipwm->duty_cycle = duty_cycle;
+
+ return 0;
+}
+
+static const struct pwm_ops raspberrypi_pwm_ops = {
+ .get_state = raspberrypi_pwm_get_state,
+ .apply = raspberrypi_pwm_apply,
+ .owner = THIS_MODULE,
+};
+
+static int raspberrypi_pwm_probe(struct platform_device *pdev)
+{
+ struct device_node *firmware_node;
+ struct device *dev = &pdev->dev;
+ struct rpi_firmware *firmware;
+ struct raspberrypi_pwm *rpipwm;
+ int ret;
+
+ firmware_node = of_get_parent(dev->of_node);
+ if (!firmware_node) {
+ dev_err(dev, "Missing firmware node\n");
+ return -ENOENT;
+ }
+
+ firmware = devm_rpi_firmware_get(&pdev->dev, firmware_node);
+ of_node_put(firmware_node);
+ if (!firmware)
+ return dev_err_probe(dev, -EPROBE_DEFER,
+ "Failed to get firmware handle\n");
+
+ rpipwm = devm_kzalloc(&pdev->dev, sizeof(*rpipwm), GFP_KERNEL);
+ if (!rpipwm)
+ return -ENOMEM;
+
+ rpipwm->firmware = firmware;
+ rpipwm->chip.dev = dev;
+ rpipwm->chip.ops = &raspberrypi_pwm_ops;
+ rpipwm->chip.base = -1;
+ rpipwm->chip.npwm = RASPBERRYPI_FIRMWARE_PWM_NUM;
+
+ platform_set_drvdata(pdev, rpipwm);
+
+ ret = raspberrypi_pwm_get_property(rpipwm->firmware, RPI_PWM_CUR_DUTY_REG,
+ &rpipwm->duty_cycle);
+ if (ret) {
+ dev_err(dev, "Failed to get duty cycle: %pe\n", ERR_PTR(ret));
+ return ret;
+ }
+
+ return pwmchip_add(&rpipwm->chip);
+}
+
+static int raspberrypi_pwm_remove(struct platform_device *pdev)
+{
+ struct raspberrypi_pwm *rpipwm = platform_get_drvdata(pdev);
+
+ return pwmchip_remove(&rpipwm->chip);
+}
+
+static const struct of_device_id raspberrypi_pwm_of_match[] = {
+ { .compatible = "raspberrypi,firmware-poe-pwm", },
+ { }
+};
+MODULE_DEVICE_TABLE(of, raspberrypi_pwm_of_match);
+
+static struct platform_driver raspberrypi_pwm_driver = {
+ .driver = {
+ .name = "raspberrypi-poe-pwm",
+ .of_match_table = raspberrypi_pwm_of_match,
+ },
+ .probe = raspberrypi_pwm_probe,
+ .remove = raspberrypi_pwm_remove,
+};
+module_platform_driver(raspberrypi_pwm_driver);
+
+MODULE_AUTHOR("Nicolas Saenz Julienne <nsaenzjulienne@suse.de>");
+MODULE_DESCRIPTION("Raspberry Pi Firmware Based PWM Bus Driver");
+MODULE_LICENSE("GPL v2");