/* * ST Microelectronics SPEAr Pulse Width Modulator driver * * Copyright (C) 2012 ST Microelectronics * Shiraz Hashim <shiraz.linux.kernel@gmail.com> * * This file is licensed under the terms of the GNU General Public * License version 2. This program is licensed "as is" without any * warranty of any kind, whether express or implied. */ #include <linux/clk.h> #include <linux/err.h> #include <linux/io.h> #include <linux/ioport.h> #include <linux/kernel.h> #include <linux/math64.h> #include <linux/module.h> #include <linux/of.h> #include <linux/platform_device.h> #include <linux/pwm.h> #include <linux/slab.h> #include <linux/types.h> #define NUM_PWM 4 /* PWM registers and bits definitions */ #define PWMCR 0x00 /* Control Register */ #define PWMCR_PWM_ENABLE 0x1 #define PWMCR_PRESCALE_SHIFT 2 #define PWMCR_MIN_PRESCALE 0x00 #define PWMCR_MAX_PRESCALE 0x3FFF #define PWMDCR 0x04 /* Duty Cycle Register */ #define PWMDCR_MIN_DUTY 0x0001 #define PWMDCR_MAX_DUTY 0xFFFF #define PWMPCR 0x08 /* Period Register */ #define PWMPCR_MIN_PERIOD 0x0001 #define PWMPCR_MAX_PERIOD 0xFFFF /* Following only available on 13xx SoCs */ #define PWMMCR 0x3C /* Master Control Register */ #define PWMMCR_PWM_ENABLE 0x1 /** * struct spear_pwm_chip - struct representing pwm chip * * @mmio_base: base address of pwm chip * @clk: pointer to clk structure of pwm chip * @chip: linux pwm chip representation */ struct spear_pwm_chip { void __iomem *mmio_base; struct clk *clk; struct pwm_chip chip; }; static inline struct spear_pwm_chip *to_spear_pwm_chip(struct pwm_chip *chip) { return container_of(chip, struct spear_pwm_chip, chip); } static inline u32 spear_pwm_readl(struct spear_pwm_chip *chip, unsigned int num, unsigned long offset) { return readl_relaxed(chip->mmio_base + (num << 4) + offset); } static inline void spear_pwm_writel(struct spear_pwm_chip *chip, unsigned int num, unsigned long offset, unsigned long val) { writel_relaxed(val, chip->mmio_base + (num << 4) + offset); } static int spear_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm, u64 duty_ns, u64 period_ns) { struct spear_pwm_chip *pc = to_spear_pwm_chip(chip); u64 val, div, clk_rate; unsigned long prescale = PWMCR_MIN_PRESCALE, pv, dc; int ret; /* * Find pv, dc and prescale to suit duty_ns and period_ns. This is done * according to formulas described below: * * period_ns = 10^9 * (PRESCALE + 1) * PV / PWM_CLK_RATE * duty_ns = 10^9 * (PRESCALE + 1) * DC / PWM_CLK_RATE * * PV = (PWM_CLK_RATE * period_ns) / (10^9 * (PRESCALE + 1)) * DC = (PWM_CLK_RATE * duty_ns) / (10^9 * (PRESCALE + 1)) */ clk_rate = clk_get_rate(pc->clk); while (1) { div = 1000000000; div *= 1 + prescale; val = clk_rate * period_ns; pv = div64_u64(val, div); val = clk_rate * duty_ns; dc = div64_u64(val, div); /* if duty_ns and period_ns are not achievable then return */ if (pv < PWMPCR_MIN_PERIOD || dc < PWMDCR_MIN_DUTY) return -EINVAL; /* * if pv and dc have crossed their upper limit, then increase * prescale and recalculate pv and dc. */ if (pv > PWMPCR_MAX_PERIOD || dc > PWMDCR_MAX_DUTY) { if (++prescale > PWMCR_MAX_PRESCALE) return -EINVAL; continue; } break; } /* * NOTE: the clock to PWM has to be enabled first before writing to the * registers. */ ret = clk_enable(pc->clk); if (ret) return ret; spear_pwm_writel(pc, pwm->hwpwm, PWMCR, prescale << PWMCR_PRESCALE_SHIFT); spear_pwm_writel(pc, pwm->hwpwm, PWMDCR, dc); spear_pwm_writel(pc, pwm->hwpwm, PWMPCR, pv); clk_disable(pc->clk); return 0; } static int spear_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm) { struct spear_pwm_chip *pc = to_spear_pwm_chip(chip); int rc = 0; u32 val; rc = clk_enable(pc->clk); if (rc) return rc; val = spear_pwm_readl(pc, pwm->hwpwm, PWMCR); val |= PWMCR_PWM_ENABLE; spear_pwm_writel(pc, pwm->hwpwm, PWMCR, val); return 0; } static void spear_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm) { struct spear_pwm_chip *pc = to_spear_pwm_chip(chip); u32 val; val = spear_pwm_readl(pc, pwm->hwpwm, PWMCR); val &= ~PWMCR_PWM_ENABLE; spear_pwm_writel(pc, pwm->hwpwm, PWMCR, val); clk_disable(pc->clk); } static int spear_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, const struct pwm_state *state) { int err; if (state->polarity != PWM_POLARITY_NORMAL) return -EINVAL; if (!state->enabled) { if (pwm->state.enabled) spear_pwm_disable(chip, pwm); return 0; } err = spear_pwm_config(chip, pwm, state->duty_cycle, state->period); if (err) return err; if (!pwm->state.enabled) return spear_pwm_enable(chip, pwm); return 0; } static const struct pwm_ops spear_pwm_ops = { .apply = spear_pwm_apply, .owner = THIS_MODULE, }; static int spear_pwm_probe(struct platform_device *pdev) { struct device_node *np = pdev->dev.of_node; struct spear_pwm_chip *pc; int ret; u32 val; pc = devm_kzalloc(&pdev->dev, sizeof(*pc), GFP_KERNEL); if (!pc) return -ENOMEM; pc->mmio_base = devm_platform_ioremap_resource(pdev, 0); if (IS_ERR(pc->mmio_base)) return PTR_ERR(pc->mmio_base); pc->clk = devm_clk_get(&pdev->dev, NULL); if (IS_ERR(pc->clk)) return PTR_ERR(pc->clk); platform_set_drvdata(pdev, pc); pc->chip.dev = &pdev->dev; pc->chip.ops = &spear_pwm_ops; pc->chip.npwm = NUM_PWM; ret = clk_prepare(pc->clk); if (ret) return ret; if (of_device_is_compatible(np, "st,spear1340-pwm")) { ret = clk_enable(pc->clk); if (ret) { clk_unprepare(pc->clk); return ret; } /* * Following enables PWM chip, channels would still be * enabled individually through their control register */ val = readl_relaxed(pc->mmio_base + PWMMCR); val |= PWMMCR_PWM_ENABLE; writel_relaxed(val, pc->mmio_base + PWMMCR); clk_disable(pc->clk); } ret = pwmchip_add(&pc->chip); if (ret < 0) { clk_unprepare(pc->clk); dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret); } return ret; } static int spear_pwm_remove(struct platform_device *pdev) { struct spear_pwm_chip *pc = platform_get_drvdata(pdev); pwmchip_remove(&pc->chip); /* clk was prepared in probe, hence unprepare it here */ clk_unprepare(pc->clk); return 0; } static const struct of_device_id spear_pwm_of_match[] = { { .compatible = "st,spear320-pwm" }, { .compatible = "st,spear1340-pwm" }, { } }; MODULE_DEVICE_TABLE(of, spear_pwm_of_match); static struct platform_driver spear_pwm_driver = { .driver = { .name = "spear-pwm", .of_match_table = spear_pwm_of_match, }, .probe = spear_pwm_probe, .remove = spear_pwm_remove, }; module_platform_driver(spear_pwm_driver); MODULE_LICENSE("GPL"); MODULE_AUTHOR("Shiraz Hashim <shiraz.linux.kernel@gmail.com>"); MODULE_AUTHOR("Viresh Kumar <viresh.kumar@linaro.com>"); MODULE_ALIAS("platform:spear-pwm");