/* * drivers/pwm/pwm-vt8500.c * * Copyright (C) 2012 Tony Prisk * Copyright (C) 2010 Alexey Charkov * * This software is licensed under the terms of the GNU General Public * License version 2, as published by the Free Software Foundation, and * may be copied, distributed, and modified under those terms. * * 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. */ #include #include #include #include #include #include #include #include #include #include #include #include #include /* * SoC architecture allocates register space for 4 PWMs but only * 2 are currently implemented. */ #define VT8500_NR_PWMS 2 #define REG_CTRL(pwm) (((pwm) << 4) + 0x00) #define REG_SCALAR(pwm) (((pwm) << 4) + 0x04) #define REG_PERIOD(pwm) (((pwm) << 4) + 0x08) #define REG_DUTY(pwm) (((pwm) << 4) + 0x0C) #define REG_STATUS 0x40 #define CTRL_ENABLE BIT(0) #define CTRL_INVERT BIT(1) #define CTRL_AUTOLOAD BIT(2) #define CTRL_STOP_IMM BIT(3) #define CTRL_LOAD_PRESCALE BIT(4) #define CTRL_LOAD_PERIOD BIT(5) #define STATUS_CTRL_UPDATE BIT(0) #define STATUS_SCALAR_UPDATE BIT(1) #define STATUS_PERIOD_UPDATE BIT(2) #define STATUS_DUTY_UPDATE BIT(3) #define STATUS_ALL_UPDATE 0x0F struct vt8500_chip { struct pwm_chip chip; void __iomem *base; struct clk *clk; }; #define to_vt8500_chip(chip) container_of(chip, struct vt8500_chip, chip) #define msecs_to_loops(t) (loops_per_jiffy / 1000 * HZ * t) static inline void pwm_busy_wait(struct vt8500_chip *vt8500, int nr, u8 bitmask) { int loops = msecs_to_loops(10); u32 mask = bitmask << (nr << 8); while ((readl(vt8500->base + REG_STATUS) & mask) && --loops) cpu_relax(); if (unlikely(!loops)) dev_warn(vt8500->chip.dev, "Waiting for status bits 0x%x to clear timed out\n", mask); } static int vt8500_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm, int duty_ns, int period_ns) { struct vt8500_chip *vt8500 = to_vt8500_chip(chip); unsigned long long c; unsigned long period_cycles, prescale, pv, dc; int err; u32 val; err = clk_enable(vt8500->clk); if (err < 0) { dev_err(chip->dev, "failed to enable clock\n"); return err; } c = clk_get_rate(vt8500->clk); c = c * period_ns; do_div(c, 1000000000); period_cycles = c; if (period_cycles < 1) period_cycles = 1; prescale = (period_cycles - 1) / 4096; pv = period_cycles / (prescale + 1) - 1; if (pv > 4095) pv = 4095; if (prescale > 1023) { clk_disable(vt8500->clk); return -EINVAL; } c = (unsigned long long)pv * duty_ns; do_div(c, period_ns); dc = c; writel(prescale, vt8500->base + REG_SCALAR(pwm->hwpwm)); pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_SCALAR_UPDATE); writel(pv, vt8500->base + REG_PERIOD(pwm->hwpwm)); pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_PERIOD_UPDATE); writel(dc, vt8500->base + REG_DUTY(pwm->hwpwm)); pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_DUTY_UPDATE); val = readl(vt8500->base + REG_CTRL(pwm->hwpwm)); val |= CTRL_AUTOLOAD; writel(val, vt8500->base + REG_CTRL(pwm->hwpwm)); pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_CTRL_UPDATE); clk_disable(vt8500->clk); return 0; } static int vt8500_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm) { struct vt8500_chip *vt8500 = to_vt8500_chip(chip); int err; u32 val; err = clk_enable(vt8500->clk); if (err < 0) { dev_err(chip->dev, "failed to enable clock\n"); return err; } val = readl(vt8500->base + REG_CTRL(pwm->hwpwm)); val |= CTRL_ENABLE; writel(val, vt8500->base + REG_CTRL(pwm->hwpwm)); pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_CTRL_UPDATE); return 0; } static void vt8500_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm) { struct vt8500_chip *vt8500 = to_vt8500_chip(chip); u32 val; val = readl(vt8500->base + REG_CTRL(pwm->hwpwm)); val &= ~CTRL_ENABLE; writel(val, vt8500->base + REG_CTRL(pwm->hwpwm)); pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_CTRL_UPDATE); clk_disable(vt8500->clk); } static int vt8500_pwm_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm, enum pwm_polarity polarity) { struct vt8500_chip *vt8500 = to_vt8500_chip(chip); u32 val; val = readl(vt8500->base + REG_CTRL(pwm->hwpwm)); if (polarity == PWM_POLARITY_INVERSED) val |= CTRL_INVERT; else val &= ~CTRL_INVERT; writel(val, vt8500->base + REG_CTRL(pwm->hwpwm)); pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_CTRL_UPDATE); return 0; } static struct pwm_ops vt8500_pwm_ops = { .enable = vt8500_pwm_enable, .disable = vt8500_pwm_disable, .config = vt8500_pwm_config, .set_polarity = vt8500_pwm_set_polarity, .owner = THIS_MODULE, }; static const struct of_device_id vt8500_pwm_dt_ids[] = { { .compatible = "via,vt8500-pwm", }, { /* Sentinel */ } }; MODULE_DEVICE_TABLE(of, vt8500_pwm_dt_ids); static int vt8500_pwm_probe(struct platform_device *pdev) { struct vt8500_chip *chip; struct resource *r; struct device_node *np = pdev->dev.of_node; int ret; if (!np) { dev_err(&pdev->dev, "invalid devicetree node\n"); return -EINVAL; } chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL); if (chip == NULL) { dev_err(&pdev->dev, "failed to allocate memory\n"); return -ENOMEM; } chip->chip.dev = &pdev->dev; chip->chip.ops = &vt8500_pwm_ops; chip->chip.of_xlate = of_pwm_xlate_with_flags; chip->chip.of_pwm_n_cells = 3; chip->chip.base = -1; chip->chip.npwm = VT8500_NR_PWMS; chip->clk = devm_clk_get(&pdev->dev, NULL); if (IS_ERR(chip->clk)) { dev_err(&pdev->dev, "clock source not specified\n"); return PTR_ERR(chip->clk); } r = platform_get_resource(pdev, IORESOURCE_MEM, 0); chip->base = devm_ioremap_resource(&pdev->dev, r); if (IS_ERR(chip->base)) return PTR_ERR(chip->base); ret = clk_prepare(chip->clk); if (ret < 0) { dev_err(&pdev->dev, "failed to prepare clock\n"); return ret; } ret = pwmchip_add(&chip->chip); if (ret < 0) { dev_err(&pdev->dev, "failed to add PWM chip\n"); return ret; } platform_set_drvdata(pdev, chip); return ret; } static int vt8500_pwm_remove(struct platform_device *pdev) { struct vt8500_chip *chip; chip = platform_get_drvdata(pdev); if (chip == NULL) return -ENODEV; clk_unprepare(chip->clk); return pwmchip_remove(&chip->chip); } static struct platform_driver vt8500_pwm_driver = { .probe = vt8500_pwm_probe, .remove = vt8500_pwm_remove, .driver = { .name = "vt8500-pwm", .owner = THIS_MODULE, .of_match_table = vt8500_pwm_dt_ids, }, }; module_platform_driver(vt8500_pwm_driver); MODULE_DESCRIPTION("VT8500 PWM Driver"); MODULE_AUTHOR("Tony Prisk "); MODULE_LICENSE("GPL v2");