diff options
Diffstat (limited to 'drivers/pwm/pwm-brcmstb.c')
| -rw-r--r-- | drivers/pwm/pwm-brcmstb.c | 343 |
1 files changed, 343 insertions, 0 deletions
diff --git a/drivers/pwm/pwm-brcmstb.c b/drivers/pwm/pwm-brcmstb.c new file mode 100644 index 000000000000..423ce087cd9c --- /dev/null +++ b/drivers/pwm/pwm-brcmstb.c @@ -0,0 +1,343 @@ +/* + * 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"); |