--- /dev/null
+/*
+ * Broadcom BCM7038 PWM driver
+ * Author: Florian Fainelli
+ *
+ * Copyright (C) 2015 Broadcom Corporation
+ *
+ * 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; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/clk.h>
+#include <linux/export.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/pwm.h>
+#include <linux/spinlock.h>
+
+#define PWM_CTRL 0x00
+#define CTRL_START BIT(0)
+#define CTRL_OEB BIT(1)
+#define CTRL_FORCE_HIGH BIT(2)
+#define CTRL_OPENDRAIN BIT(3)
+#define CTRL_CHAN_OFFS 4
+
+#define PWM_CTRL2 0x04
+#define CTRL2_OUT_SELECT BIT(0)
+
+#define PWM_CH_SIZE 0x8
+
+#define PWM_CWORD_MSB(ch) (0x08 + ((ch) * PWM_CH_SIZE))
+#define PWM_CWORD_LSB(ch) (0x0c + ((ch) * PWM_CH_SIZE))
+
+/* Number of bits for the CWORD value */
+#define CWORD_BIT_SIZE 16
+
+/*
+ * Maximum control word value allowed when variable-frequency PWM is used as a
+ * clock for the constant-frequency PMW.
+ */
+#define CONST_VAR_F_MAX 32768
+#define CONST_VAR_F_MIN 1
+
+#define PWM_ON(ch) (0x18 + ((ch) * PWM_CH_SIZE))
+#define PWM_ON_MIN 1
+#define PWM_PERIOD(ch) (0x1c + ((ch) * PWM_CH_SIZE))
+#define PWM_PERIOD_MIN 0
+
+#define PWM_ON_PERIOD_MAX 0xff
+
+struct brcmstb_pwm {
+ void __iomem *base;
+ spinlock_t lock;
+ struct clk *clk;
+ struct pwm_chip chip;
+};
+
+static inline u32 brcmstb_pwm_readl(struct brcmstb_pwm *p,
+ unsigned int offset)
+{
+ if (IS_ENABLED(CONFIG_MIPS) && IS_ENABLED(CONFIG_CPU_BIG_ENDIAN))
+ return __raw_readl(p->base + offset);
+ else
+ return readl_relaxed(p->base + offset);
+}
+
+static inline void brcmstb_pwm_writel(struct brcmstb_pwm *p, u32 value,
+ unsigned int offset)
+{
+ if (IS_ENABLED(CONFIG_MIPS) && IS_ENABLED(CONFIG_CPU_BIG_ENDIAN))
+ __raw_writel(value, p->base + offset);
+ else
+ writel_relaxed(value, p->base + offset);
+}
+
+static inline struct brcmstb_pwm *to_brcmstb_pwm(struct pwm_chip *chip)
+{
+ return container_of(chip, struct brcmstb_pwm, chip);
+}
+
+/*
+ * Fv is derived from the variable frequency output. The variable frequency
+ * output is configured using this formula:
+ *
+ * W = cword, if cword < 2 ^ 15 else 16-bit 2's complement of cword
+ *
+ * Fv = W x 2 ^ -16 x 27Mhz (reference clock)
+ *
+ * The period is: (period + 1) / Fv and "on" time is on / (period + 1)
+ *
+ * The PWM core framework specifies that the "duty_ns" parameter is in fact the
+ * "on" time, so this translates directly into our HW programming here.
+ */
+static int brcmstb_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
+ int duty_ns, int period_ns)
+{
+ struct brcmstb_pwm *p = to_brcmstb_pwm(chip);
+ unsigned long pc, dc, cword = CONST_VAR_F_MAX;
+ unsigned int channel = pwm->hwpwm;
+ u32 value;
+
+ /*
+ * If asking for a duty_ns equal to period_ns, we need to substract
+ * the period value by 1 to make it shorter than the "on" time and
+ * produce a flat 100% duty cycle signal, and max out the "on" time
+ */
+ if (duty_ns == period_ns) {
+ dc = PWM_ON_PERIOD_MAX;
+ pc = PWM_ON_PERIOD_MAX - 1;
+ goto done;
+ }
+
+ while (1) {
+ u64 rate, tmp;
+
+ /*
+ * Calculate the base rate from base frequency and current
+ * cword
+ */
+ rate = (u64)clk_get_rate(p->clk) * (u64)cword;
+ do_div(rate, 1 << CWORD_BIT_SIZE);
+
+ tmp = period_ns * rate;
+ do_div(tmp, NSEC_PER_SEC);
+ pc = tmp;
+
+ tmp = (duty_ns + 1) * rate;
+ do_div(tmp, NSEC_PER_SEC);
+ dc = tmp;
+
+ /*
+ * We can be called with separate duty and period updates,
+ * so do not reject dc == 0 right away
+ */
+ if (pc == PWM_PERIOD_MIN || (dc < PWM_ON_MIN && duty_ns))
+ return -EINVAL;
+
+ /* We converged on a calculation */
+ if (pc <= PWM_ON_PERIOD_MAX && dc <= PWM_ON_PERIOD_MAX)
+ break;
+
+ /*
+ * The cword needs to be a power of 2 for the variable
+ * frequency generator to output a 50% duty cycle variable
+ * frequency which is used as input clock to the fixed
+ * frequency generator.
+ */
+ cword >>= 1;
+
+ /*
+ * Desired periods are too large, we do not have a divider
+ * for them
+ */
+ if (cword < CONST_VAR_F_MIN)
+ return -EINVAL;
+ }
+
+done:
+ /*
+ * Configure the defined "cword" value to have the variable frequency
+ * generator output a base frequency for the constant frequency
+ * generator to derive from.
+ */
+ spin_lock(&p->lock);
+ brcmstb_pwm_writel(p, cword >> 8, PWM_CWORD_MSB(channel));
+ brcmstb_pwm_writel(p, cword & 0xff, PWM_CWORD_LSB(channel));
+
+ /* Select constant frequency signal output */
+ value = brcmstb_pwm_readl(p, PWM_CTRL2);
+ value |= CTRL2_OUT_SELECT << (channel * CTRL_CHAN_OFFS);
+ brcmstb_pwm_writel(p, value, PWM_CTRL2);
+
+ /* Configure on and period value */
+ brcmstb_pwm_writel(p, pc, PWM_PERIOD(channel));
+ brcmstb_pwm_writel(p, dc, PWM_ON(channel));
+ spin_unlock(&p->lock);
+
+ return 0;
+}
+
+static inline void brcmstb_pwm_enable_set(struct brcmstb_pwm *p,
+ unsigned int channel, bool enable)
+{
+ unsigned int shift = channel * CTRL_CHAN_OFFS;
+ u32 value;
+
+ spin_lock(&p->lock);
+ value = brcmstb_pwm_readl(p, PWM_CTRL);
+
+ if (enable) {
+ value &= ~(CTRL_OEB << shift);
+ value |= (CTRL_START | CTRL_OPENDRAIN) << shift;
+ } else {
+ value &= ~((CTRL_START | CTRL_OPENDRAIN) << shift);
+ value |= CTRL_OEB << shift;
+ }
+
+ brcmstb_pwm_writel(p, value, PWM_CTRL);
+ spin_unlock(&p->lock);
+}
+
+static int brcmstb_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+ struct brcmstb_pwm *p = to_brcmstb_pwm(chip);
+
+ brcmstb_pwm_enable_set(p, pwm->hwpwm, true);
+
+ return 0;
+}
+
+static void brcmstb_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+ struct brcmstb_pwm *p = to_brcmstb_pwm(chip);
+
+ brcmstb_pwm_enable_set(p, pwm->hwpwm, false);
+}
+
+static const struct pwm_ops brcmstb_pwm_ops = {
+ .config = brcmstb_pwm_config,
+ .enable = brcmstb_pwm_enable,
+ .disable = brcmstb_pwm_disable,
+ .owner = THIS_MODULE,
+};
+
+static const struct of_device_id brcmstb_pwm_of_match[] = {
+ { .compatible = "brcm,bcm7038-pwm", },
+ { /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, brcmstb_pwm_of_match);
+
+static int brcmstb_pwm_probe(struct platform_device *pdev)
+{
+ struct brcmstb_pwm *p;
+ struct resource *res;
+ int ret;
+
+ p = devm_kzalloc(&pdev->dev, sizeof(*p), GFP_KERNEL);
+ if (!p)
+ return -ENOMEM;
+
+ spin_lock_init(&p->lock);
+
+ p->clk = devm_clk_get(&pdev->dev, NULL);
+ if (IS_ERR(p->clk)) {
+ dev_err(&pdev->dev, "failed to obtain clock\n");
+ return PTR_ERR(p->clk);
+ }
+
+ ret = clk_prepare_enable(p->clk);
+ if (ret < 0) {
+ dev_err(&pdev->dev, "failed to enable clock: %d\n", ret);
+ return ret;
+ }
+
+ platform_set_drvdata(pdev, p);
+
+ p->chip.dev = &pdev->dev;
+ p->chip.ops = &brcmstb_pwm_ops;
+ p->chip.base = -1;
+ p->chip.npwm = 2;
+ p->chip.can_sleep = true;
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ p->base = devm_ioremap_resource(&pdev->dev, res);
+ if (!p->base) {
+ ret = -ENOMEM;
+ goto out_clk;
+ }
+
+ ret = pwmchip_add(&p->chip);
+ if (ret) {
+ dev_err(&pdev->dev, "failed to add PWM chip: %d\n", ret);
+ goto out_clk;
+ }
+
+ return 0;
+
+out_clk:
+ clk_disable_unprepare(p->clk);
+ return ret;
+}
+
+static int brcmstb_pwm_remove(struct platform_device *pdev)
+{
+ struct brcmstb_pwm *p = platform_get_drvdata(pdev);
+ int ret;
+
+ ret = pwmchip_remove(&p->chip);
+ clk_disable_unprepare(p->clk);
+
+ return ret;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int brcmstb_pwm_suspend(struct device *dev)
+{
+ struct brcmstb_pwm *p = dev_get_drvdata(dev);
+
+ clk_disable(p->clk);
+
+ return 0;
+}
+
+static int brcmstb_pwm_resume(struct device *dev)
+{
+ struct brcmstb_pwm *p = dev_get_drvdata(dev);
+
+ clk_enable(p->clk);
+
+ return 0;
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(brcmstb_pwm_pm_ops, brcmstb_pwm_suspend,
+ brcmstb_pwm_resume);
+
+static struct platform_driver brcmstb_pwm_driver = {
+ .probe = brcmstb_pwm_probe,
+ .remove = brcmstb_pwm_remove,
+ .driver = {
+ .name = "pwm-brcmstb",
+ .of_match_table = brcmstb_pwm_of_match,
+ .pm = &brcmstb_pwm_pm_ops,
+ },
+};
+module_platform_driver(brcmstb_pwm_driver);
+
+MODULE_AUTHOR("Florian Fainelli <f.fainelli@gmail.com>");
+MODULE_DESCRIPTION("Broadcom STB PWM driver");
+MODULE_ALIAS("platform:pwm-brcmstb");
+MODULE_LICENSE("GPL");
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