pwm: Add support for Broadcom iProc PWM controller
Add support for the PWM controller present in Broadcom's iProc family of
SoCs. It has been tested on the Northstar+ bcm958625HR board.
Signed-off-by: Yendapally Reddy Dhananjaya Reddy <yendapally.reddy@broadcom.com>
[thierry.reding@gmail.com: bunch of coding style fixes, cleanups]
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
diff --git a/drivers/pwm/pwm-bcm-iproc.c b/drivers/pwm/pwm-bcm-iproc.c
new file mode 100644
index 0000000..d961a82
--- /dev/null
+++ b/drivers/pwm/pwm-bcm-iproc.c
@@ -0,0 +1,277 @@
+/*
+ * Copyright (C) 2016 Broadcom
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation version 2.
+ *
+ * This program is distributed "as is" WITHOUT ANY WARRANTY of any
+ * kind, whether express or implied; without even the implied warranty
+ * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/math64.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/pwm.h>
+
+#define IPROC_PWM_CTRL_OFFSET 0x00
+#define IPROC_PWM_CTRL_TYPE_SHIFT(ch) (15 + (ch))
+#define IPROC_PWM_CTRL_POLARITY_SHIFT(ch) (8 + (ch))
+#define IPROC_PWM_CTRL_EN_SHIFT(ch) (ch)
+
+#define IPROC_PWM_PERIOD_OFFSET(ch) (0x04 + ((ch) << 3))
+#define IPROC_PWM_PERIOD_MIN 0x02
+#define IPROC_PWM_PERIOD_MAX 0xffff
+
+#define IPROC_PWM_DUTY_CYCLE_OFFSET(ch) (0x08 + ((ch) << 3))
+#define IPROC_PWM_DUTY_CYCLE_MIN 0x00
+#define IPROC_PWM_DUTY_CYCLE_MAX 0xffff
+
+#define IPROC_PWM_PRESCALE_OFFSET 0x24
+#define IPROC_PWM_PRESCALE_BITS 0x06
+#define IPROC_PWM_PRESCALE_SHIFT(ch) ((3 - (ch)) * \
+ IPROC_PWM_PRESCALE_BITS)
+#define IPROC_PWM_PRESCALE_MASK(ch) (IPROC_PWM_PRESCALE_MAX << \
+ IPROC_PWM_PRESCALE_SHIFT(ch))
+#define IPROC_PWM_PRESCALE_MIN 0x00
+#define IPROC_PWM_PRESCALE_MAX 0x3f
+
+struct iproc_pwmc {
+ struct pwm_chip chip;
+ void __iomem *base;
+ struct clk *clk;
+};
+
+static inline struct iproc_pwmc *to_iproc_pwmc(struct pwm_chip *chip)
+{
+ return container_of(chip, struct iproc_pwmc, chip);
+}
+
+static void iproc_pwmc_enable(struct iproc_pwmc *ip, unsigned int channel)
+{
+ u32 value;
+
+ value = readl(ip->base + IPROC_PWM_CTRL_OFFSET);
+ value |= 1 << IPROC_PWM_CTRL_EN_SHIFT(channel);
+ writel(value, ip->base + IPROC_PWM_CTRL_OFFSET);
+
+ /* must be a 400 ns delay between clearing and setting enable bit */
+ ndelay(400);
+}
+
+static void iproc_pwmc_disable(struct iproc_pwmc *ip, unsigned int channel)
+{
+ u32 value;
+
+ value = readl(ip->base + IPROC_PWM_CTRL_OFFSET);
+ value &= ~(1 << IPROC_PWM_CTRL_EN_SHIFT(channel));
+ writel(value, ip->base + IPROC_PWM_CTRL_OFFSET);
+
+ /* must be a 400 ns delay between clearing and setting enable bit */
+ ndelay(400);
+}
+
+static void iproc_pwmc_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
+ struct pwm_state *state)
+{
+ struct iproc_pwmc *ip = to_iproc_pwmc(chip);
+ u64 tmp, multi, rate;
+ u32 value, prescale;
+
+ rate = clk_get_rate(ip->clk);
+
+ value = readl(ip->base + IPROC_PWM_CTRL_OFFSET);
+
+ if (value & BIT(IPROC_PWM_CTRL_EN_SHIFT(pwm->hwpwm)))
+ state->enabled = true;
+ else
+ state->enabled = false;
+
+ if (value & BIT(IPROC_PWM_CTRL_POLARITY_SHIFT(pwm->hwpwm)))
+ state->polarity = PWM_POLARITY_NORMAL;
+ else
+ state->polarity = PWM_POLARITY_INVERSED;
+
+ value = readl(ip->base + IPROC_PWM_PRESCALE_OFFSET);
+ prescale = value >> IPROC_PWM_PRESCALE_SHIFT(pwm->hwpwm);
+ prescale &= IPROC_PWM_PRESCALE_MAX;
+
+ multi = NSEC_PER_SEC * (prescale + 1);
+
+ value = readl(ip->base + IPROC_PWM_PERIOD_OFFSET(pwm->hwpwm));
+ tmp = (value & IPROC_PWM_PERIOD_MAX) * multi;
+ state->period = div64_u64(tmp, rate);
+
+ value = readl(ip->base + IPROC_PWM_DUTY_CYCLE_OFFSET(pwm->hwpwm));
+ tmp = (value & IPROC_PWM_PERIOD_MAX) * multi;
+ state->duty_cycle = div64_u64(tmp, rate);
+}
+
+static int iproc_pwmc_apply(struct pwm_chip *chip, struct pwm_device *pwm,
+ struct pwm_state *state)
+{
+ unsigned long prescale = IPROC_PWM_PRESCALE_MIN;
+ struct iproc_pwmc *ip = to_iproc_pwmc(chip);
+ u32 value, period, duty;
+ u64 rate;
+
+ rate = clk_get_rate(ip->clk);
+
+ /*
+ * Find period count, duty count and prescale to suit duty_cycle and
+ * period. This is done according to formulas described below:
+ *
+ * period_ns = 10^9 * (PRESCALE + 1) * PC / PWM_CLK_RATE
+ * duty_ns = 10^9 * (PRESCALE + 1) * DC / PWM_CLK_RATE
+ *
+ * PC = (PWM_CLK_RATE * period_ns) / (10^9 * (PRESCALE + 1))
+ * DC = (PWM_CLK_RATE * duty_ns) / (10^9 * (PRESCALE + 1))
+ */
+ while (1) {
+ u64 value, div;
+
+ div = NSEC_PER_SEC * (prescale + 1);
+ value = rate * state->period;
+ period = div64_u64(value, div);
+ value = rate * state->duty_cycle;
+ duty = div64_u64(value, div);
+
+ if (period < IPROC_PWM_PERIOD_MIN ||
+ duty < IPROC_PWM_DUTY_CYCLE_MIN)
+ return -EINVAL;
+
+ if (period <= IPROC_PWM_PERIOD_MAX &&
+ duty <= IPROC_PWM_DUTY_CYCLE_MAX)
+ break;
+
+ /* Otherwise, increase prescale and recalculate counts */
+ if (++prescale > IPROC_PWM_PRESCALE_MAX)
+ return -EINVAL;
+ }
+
+ iproc_pwmc_disable(ip, pwm->hwpwm);
+
+ /* Set prescale */
+ value = readl(ip->base + IPROC_PWM_PRESCALE_OFFSET);
+ value &= ~IPROC_PWM_PRESCALE_MASK(pwm->hwpwm);
+ value |= prescale << IPROC_PWM_PRESCALE_SHIFT(pwm->hwpwm);
+ writel(value, ip->base + IPROC_PWM_PRESCALE_OFFSET);
+
+ /* set period and duty cycle */
+ writel(period, ip->base + IPROC_PWM_PERIOD_OFFSET(pwm->hwpwm));
+ writel(duty, ip->base + IPROC_PWM_DUTY_CYCLE_OFFSET(pwm->hwpwm));
+
+ /* set polarity */
+ value = readl(ip->base + IPROC_PWM_CTRL_OFFSET);
+
+ if (state->polarity == PWM_POLARITY_NORMAL)
+ value |= 1 << IPROC_PWM_CTRL_POLARITY_SHIFT(pwm->hwpwm);
+ else
+ value &= ~(1 << IPROC_PWM_CTRL_POLARITY_SHIFT(pwm->hwpwm));
+
+ writel(value, ip->base + IPROC_PWM_CTRL_OFFSET);
+
+ if (state->enabled)
+ iproc_pwmc_enable(ip, pwm->hwpwm);
+
+ return 0;
+}
+
+static const struct pwm_ops iproc_pwm_ops = {
+ .apply = iproc_pwmc_apply,
+ .get_state = iproc_pwmc_get_state,
+};
+
+static int iproc_pwmc_probe(struct platform_device *pdev)
+{
+ struct iproc_pwmc *ip;
+ struct resource *res;
+ unsigned int i;
+ u32 value;
+ int ret;
+
+ ip = devm_kzalloc(&pdev->dev, sizeof(*ip), GFP_KERNEL);
+ if (!ip)
+ return -ENOMEM;
+
+ platform_set_drvdata(pdev, ip);
+
+ ip->chip.dev = &pdev->dev;
+ ip->chip.ops = &iproc_pwm_ops;
+ ip->chip.base = -1;
+ ip->chip.npwm = 4;
+ ip->chip.of_xlate = of_pwm_xlate_with_flags;
+ ip->chip.of_pwm_n_cells = 3;
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ ip->base = devm_ioremap_resource(&pdev->dev, res);
+ if (IS_ERR(ip->base))
+ return PTR_ERR(ip->base);
+
+ ip->clk = devm_clk_get(&pdev->dev, NULL);
+ if (IS_ERR(ip->clk)) {
+ dev_err(&pdev->dev, "failed to get clock: %ld\n",
+ PTR_ERR(ip->clk));
+ return PTR_ERR(ip->clk);
+ }
+
+ ret = clk_prepare_enable(ip->clk);
+ if (ret < 0) {
+ dev_err(&pdev->dev, "failed to enable clock: %d\n", ret);
+ return ret;
+ }
+
+ /* Set full drive and normal polarity for all channels */
+ value = readl(ip->base + IPROC_PWM_CTRL_OFFSET);
+
+ for (i = 0; i < ip->chip.npwm; i++) {
+ value &= ~(1 << IPROC_PWM_CTRL_TYPE_SHIFT(i));
+ value |= 1 << IPROC_PWM_CTRL_POLARITY_SHIFT(i);
+ }
+
+ writel(value, ip->base + IPROC_PWM_CTRL_OFFSET);
+
+ ret = pwmchip_add(&ip->chip);
+ if (ret < 0) {
+ dev_err(&pdev->dev, "failed to add PWM chip: %d\n", ret);
+ clk_disable_unprepare(ip->clk);
+ }
+
+ return ret;
+}
+
+static int iproc_pwmc_remove(struct platform_device *pdev)
+{
+ struct iproc_pwmc *ip = platform_get_drvdata(pdev);
+
+ clk_disable_unprepare(ip->clk);
+
+ return pwmchip_remove(&ip->chip);
+}
+
+static const struct of_device_id bcm_iproc_pwmc_dt[] = {
+ { .compatible = "brcm,iproc-pwm" },
+ { },
+};
+MODULE_DEVICE_TABLE(of, bcm_iproc_pwmc_dt);
+
+static struct platform_driver iproc_pwmc_driver = {
+ .driver = {
+ .name = "bcm-iproc-pwm",
+ .of_match_table = bcm_iproc_pwmc_dt,
+ },
+ .probe = iproc_pwmc_probe,
+ .remove = iproc_pwmc_remove,
+};
+module_platform_driver(iproc_pwmc_driver);
+
+MODULE_AUTHOR("Yendapally Reddy Dhananjaya Reddy <yendapally.reddy@broadcom.com>");
+MODULE_DESCRIPTION("Broadcom iProc PWM driver");
+MODULE_LICENSE("GPL v2");
