[PATCH v5 2/4] pwm: Add Apple PWM controller

Sasha Finkelstein
2022-12-21T21:07:34Z

Adds the Apple PWM controller driver.

Signed-off-by: Sasha Finkelstein <fnkl.kernel@gmail.com>
Acked-by: Sven Peter <sven@svenpeter.dev>
---
drivers/pwm/Kconfig | 12 ++++
drivers/pwm/Makefile | 1 +
drivers/pwm/pwm-apple.c | 154 ++++++++++++++++++++++++++++++++++++++++
3 files changed, 167 insertions(+)
create mode 100644 drivers/pwm/pwm-apple.c

diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index 60d13a949bc5..c3be11468414 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -51,6 +51,18 @@ config PWM_AB8500
To compile this driver as a module, choose M here: the module
will be called pwm-ab8500.

+config PWM_APPLE
+ tristate "Apple SoC PWM support"
+ depends on ARCH_APPLE || COMPILE_TEST
+ help
+ Generic PWM framework driver for PWM controller present on
+ Apple SoCs
+
+ Say Y here if you have an ARM Apple laptop, otherwise say N
+
+ To compile this driver as a module, choose M here: the module
+ will be called pwm-apple.
+
config PWM_ATMEL
tristate "Atmel PWM support"
depends on ARCH_AT91 || COMPILE_TEST
diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
index 7bf1a29f02b8..19899b912e00 100644
--- a/drivers/pwm/Makefile
+++ b/drivers/pwm/Makefile
@@ -2,6 +2,7 @@
obj-$(CONFIG_PWM) += core.o
obj-$(CONFIG_PWM_SYSFS) += sysfs.o
obj-$(CONFIG_PWM_AB8500) += pwm-ab8500.o
+obj-$(CONFIG_PWM_APPLE) += pwm-apple.o
obj-$(CONFIG_PWM_ATMEL) += pwm-atmel.o
obj-$(CONFIG_PWM_ATMEL_HLCDC_PWM) += pwm-atmel-hlcdc.o
obj-$(CONFIG_PWM_ATMEL_TCB) += pwm-atmel-tcb.o
diff --git a/drivers/pwm/pwm-apple.c b/drivers/pwm/pwm-apple.c
new file mode 100644
index 000000000000..09048b02b2f5
--- /dev/null
+++ b/drivers/pwm/pwm-apple.c
@@ -0,0 +1,154 @@
+// SPDX-License-Identifier: GPL-2.0 OR MIT
+/*
+ * Driver for the Apple SoC PWM controller
+ *
+ * Copyright The Asahi Linux Contributors
+ *
+ * Limitations:
+ * - The writes to cycle registers are shadowed until a write to
+ * the control register.
+ * - If both OFF_CYCLES and ON_CYCLES are set to 0, the output
+ * is a constant off signal.
+ */
+
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/pwm.h>
+#include <linux/io.h>
+#include <linux/clk.h>
+#include <linux/math64.h>
+
+#define APPLE_PWM_CTRL 0x00
+#define APPLE_PWM_ON_CYCLES 0x1c
+#define APPLE_PWM_OFF_CYCLES 0x18
+
+#define APPLE_CTRL_ENABLE BIT(0)
+#define APPLE_CTRL_MODE BIT(2)
+#define APPLE_CTRL_UPDATE BIT(5)
+#define APPLE_CTRL_TRIGGER BIT(9)
+#define APPLE_CTRL_INVERT BIT(10)
+#define APPLE_CTRL_OUTPUT_ENABLE BIT(14)
+
+struct apple_pwm {
+ struct pwm_chip chip;
+ void __iomem *base;
+ u64 clkrate;
+};
+
+static inline struct apple_pwm *to_apple_pwm(struct pwm_chip *chip)
+{
+ return container_of(chip, struct apple_pwm, chip);
+}
+
+static int apple_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
+ const struct pwm_state *state)
+{
+ struct apple_pwm *fpwm;
+
+ if (state->polarity == PWM_POLARITY_INVERSED)
+ return -EINVAL;
+
+ fpwm = to_apple_pwm(chip);
+ if (state->enabled) {
+ u64 on_cycles, off_cycles;
+
+ on_cycles = mul_u64_u64_div_u64(fpwm->clkrate,
+ state->duty_cycle, NSEC_PER_SEC);
+ if (on_cycles > 0xFFFFFFFF)
+ return -ERANGE;
+
+ off_cycles = mul_u64_u64_div_u64(fpwm->clkrate,
+ state->period, NSEC_PER_SEC) - on_cycles;
+ if (off_cycles > 0xFFFFFFFF)
+ return -ERANGE;
+
+ writel(on_cycles, fpwm->base + APPLE_PWM_ON_CYCLES);
+ writel(off_cycles, fpwm->base + APPLE_PWM_OFF_CYCLES);
+ writel(APPLE_CTRL_ENABLE | APPLE_CTRL_OUTPUT_ENABLE | APPLE_CTRL_UPDATE,
+ fpwm->base + APPLE_PWM_CTRL);
+ } else {
+ writel(0, fpwm->base + APPLE_PWM_CTRL);
+ }
+ return 0;
+}
+
+static void apple_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
+ struct pwm_state *state)
+{
+ struct apple_pwm *fpwm;
+ u32 on_cycles, off_cycles, ctrl;
+
+ fpwm = to_apple_pwm(chip);
+
+ ctrl = readl(fpwm->base + APPLE_PWM_CTRL);
+ on_cycles = readl(fpwm->base + APPLE_PWM_ON_CYCLES);
+ off_cycles = readl(fpwm->base + APPLE_PWM_OFF_CYCLES);
+
+ state->enabled = (ctrl & APPLE_CTRL_ENABLE) && (ctrl & APPLE_CTRL_OUTPUT_ENABLE);
+ state->polarity = PWM_POLARITY_NORMAL;
+ // on_cycles + off_cycles is 33 bits, NSEC_PER_SEC is 30, there is no overflow
+ state->duty_cycle = DIV64_U64_ROUND_UP((u64)on_cycles * NSEC_PER_SEC, fpwm->clkrate);
+ state->period = DIV64_U64_ROUND_UP(((u64)off_cycles + (u64)on_cycles) *
+ NSEC_PER_SEC, fpwm->clkrate);
+}
+
+static const struct pwm_ops apple_pwm_ops = {
+ .apply = apple_pwm_apply,
+ .get_state = apple_pwm_get_state,
+ .owner = THIS_MODULE,
+};
+
+static int apple_pwm_probe(struct platform_device *pdev)
+{
+ struct apple_pwm *fpwm;
+ struct clk *clk;
+ int ret;
+
+ fpwm = devm_kzalloc(&pdev->dev, sizeof(*fpwm), GFP_KERNEL);
+ if (!fpwm)
+ return -ENOMEM;
+
+ fpwm->base = devm_platform_ioremap_resource(pdev, 0);
+ if (IS_ERR(fpwm->base))
+ return dev_err_probe(&pdev->dev, PTR_ERR(fpwm->base), "unable to map mmio");
+
+ clk = devm_clk_get_enabled(&pdev->dev, NULL);
+ if (IS_ERR(clk))
+ return dev_err_probe(&pdev->dev, PTR_ERR(clk), "unable to get the clock");
+
+ /*
+ * uses the 24MHz system clock on all existing devices, can only
+ * happen if the device tree is broken
+ */
+ fpwm->clkrate = clk_get_rate(clk);
+ if (fpwm->clkrate > NSEC_PER_SEC)
+ return dev_err_probe(&pdev->dev, -EINVAL, "pwm clock out of range");
+
+ fpwm->chip.dev = &pdev->dev;
+ fpwm->chip.npwm = 1;
+ fpwm->chip.ops = &apple_pwm_ops;
+
+ ret = devm_pwmchip_add(&pdev->dev, &fpwm->chip);
+ if (ret < 0)
+ return dev_err_probe(&pdev->dev, ret, "unable to add pwm chip");
+
+ return 0;
+}
+
+static const struct of_device_id apple_pwm_of_match[] = {
+ { .compatible = "apple,s5l-fpwm" },
+ {}
+};
+MODULE_DEVICE_TABLE(of, apple_pwm_of_match);
+
+static struct platform_driver apple_pwm_driver = {
+ .probe = apple_pwm_probe,
+ .driver = {
+ .name = "apple-pwm",
+ .of_match_table = apple_pwm_of_match,
+ },
+};
+module_platform_driver(apple_pwm_driver);
+
+MODULE_DESCRIPTION("Apple SoC PWM driver");
+MODULE_LICENSE("Dual MIT/GPL");
--
2.37.1 (Apple Git-137.1)