/* * 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 (IS_ERR(p->base)) { ret = PTR_ERR(p->base); 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");