/* * simple driver for PWM (Pulse Width Modulator) controller * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. * * Derived from pxa PWM driver by eric miao */ #include #include #include #include #include #include #include #include #include #include #include /* i.MX1 and i.MX21 share the same PWM function block: */ #define MX1_PWMC 0x00 /* PWM Control Register */ #define MX1_PWMS 0x04 /* PWM Sample Register */ #define MX1_PWMP 0x08 /* PWM Period Register */ #define MX1_PWMC_EN (1 << 4) /* i.MX27, i.MX31, i.MX35 share the same PWM function block: */ #define MX3_PWMCR 0x00 /* PWM Control Register */ #define MX3_PWMSR 0x04 /* PWM Status Register */ #define MX3_PWMSAR 0x0C /* PWM Sample Register */ #define MX3_PWMPR 0x10 /* PWM Period Register */ #define MX3_PWMCR_PRESCALER(x) ((((x) - 1) & 0xFFF) << 4) #define MX3_PWMCR_DOZEEN (1 << 24) #define MX3_PWMCR_WAITEN (1 << 23) #define MX3_PWMCR_DBGEN (1 << 22) #define MX3_PWMCR_POUTC (1 << 18) #define MX3_PWMCR_CLKSRC_IPG_HIGH (2 << 16) #define MX3_PWMCR_CLKSRC_IPG (1 << 16) #define MX3_PWMCR_SWR (1 << 3) #define MX3_PWMCR_EN (1 << 0) #define MX3_PWMSR_FIFOAV_4WORDS 0x4 #define MX3_PWMSR_FIFOAV_MASK 0x7 #define MX3_PWM_SWR_LOOP 5 struct imx_chip { struct clk *clk_per; void __iomem *mmio_base; struct pwm_chip chip; }; #define to_imx_chip(chip) container_of(chip, struct imx_chip, chip) static int imx_pwm_config_v1(struct pwm_chip *chip, struct pwm_device *pwm, int duty_ns, int period_ns) { struct imx_chip *imx = to_imx_chip(chip); /* * The PWM subsystem allows for exact frequencies. However, * I cannot connect a scope on my device to the PWM line and * thus cannot provide the program the PWM controller * exactly. Instead, I'm relying on the fact that the * Bootloader (u-boot or WinCE+haret) has programmed the PWM * function group already. So I'll just modify the PWM sample * register to follow the ratio of duty_ns vs. period_ns * accordingly. * * This is good enough for programming the brightness of * the LCD backlight. * * The real implementation would divide PERCLK[0] first by * both the prescaler (/1 .. /128) and then by CLKSEL * (/2 .. /16). */ u32 max = readl(imx->mmio_base + MX1_PWMP); u32 p = max * duty_ns / period_ns; writel(max - p, imx->mmio_base + MX1_PWMS); return 0; } static int imx_pwm_enable_v1(struct pwm_chip *chip, struct pwm_device *pwm) { struct imx_chip *imx = to_imx_chip(chip); u32 val; int ret; ret = clk_prepare_enable(imx->clk_per); if (ret < 0) return ret; val = readl(imx->mmio_base + MX1_PWMC); val |= MX1_PWMC_EN; writel(val, imx->mmio_base + MX1_PWMC); return 0; } static void imx_pwm_disable_v1(struct pwm_chip *chip, struct pwm_device *pwm) { struct imx_chip *imx = to_imx_chip(chip); u32 val; val = readl(imx->mmio_base + MX1_PWMC); val &= ~MX1_PWMC_EN; writel(val, imx->mmio_base + MX1_PWMC); clk_disable_unprepare(imx->clk_per); } static void imx_pwm_sw_reset(struct pwm_chip *chip) { struct imx_chip *imx = to_imx_chip(chip); struct device *dev = chip->dev; int wait_count = 0; u32 cr; writel(MX3_PWMCR_SWR, imx->mmio_base + MX3_PWMCR); do { usleep_range(200, 1000); cr = readl(imx->mmio_base + MX3_PWMCR); } while ((cr & MX3_PWMCR_SWR) && (wait_count++ < MX3_PWM_SWR_LOOP)); if (cr & MX3_PWMCR_SWR) dev_warn(dev, "software reset timeout\n"); } static void imx_pwm_wait_fifo_slot(struct pwm_chip *chip, struct pwm_device *pwm) { struct imx_chip *imx = to_imx_chip(chip); struct device *dev = chip->dev; unsigned int period_ms; int fifoav; u32 sr; sr = readl(imx->mmio_base + MX3_PWMSR); fifoav = sr & MX3_PWMSR_FIFOAV_MASK; if (fifoav == MX3_PWMSR_FIFOAV_4WORDS) { period_ms = DIV_ROUND_UP(pwm_get_period(pwm), NSEC_PER_MSEC); msleep(period_ms); sr = readl(imx->mmio_base + MX3_PWMSR); if (fifoav == (sr & MX3_PWMSR_FIFOAV_MASK)) dev_warn(dev, "there is no free FIFO slot\n"); } } static int imx_pwm_apply_v2(struct pwm_chip *chip, struct pwm_device *pwm, struct pwm_state *state) { unsigned long period_cycles, duty_cycles, prescale; struct imx_chip *imx = to_imx_chip(chip); struct pwm_state cstate; unsigned long long c; int ret; u32 cr; pwm_get_state(pwm, &cstate); if (state->enabled) { c = clk_get_rate(imx->clk_per); c *= state->period; do_div(c, 1000000000); period_cycles = c; prescale = period_cycles / 0x10000 + 1; period_cycles /= prescale; c = (unsigned long long)period_cycles * state->duty_cycle; do_div(c, state->period); duty_cycles = c; /* * according to imx pwm RM, the real period value should be * PERIOD value in PWMPR plus 2. */ if (period_cycles > 2) period_cycles -= 2; else period_cycles = 0; /* * Wait for a free FIFO slot if the PWM is already enabled, and * flush the FIFO if the PWM was disabled and is about to be * enabled. */ if (cstate.enabled) { imx_pwm_wait_fifo_slot(chip, pwm); } else { ret = clk_prepare_enable(imx->clk_per); if (ret) return ret; imx_pwm_sw_reset(chip); } writel(duty_cycles, imx->mmio_base + MX3_PWMSAR); writel(period_cycles, imx->mmio_base + MX3_PWMPR); cr = MX3_PWMCR_PRESCALER(prescale) | MX3_PWMCR_DOZEEN | MX3_PWMCR_WAITEN | MX3_PWMCR_DBGEN | MX3_PWMCR_CLKSRC_IPG_HIGH | MX3_PWMCR_EN; if (state->polarity == PWM_POLARITY_INVERSED) cr |= MX3_PWMCR_POUTC; writel(cr, imx->mmio_base + MX3_PWMCR); } else if (cstate.enabled) { writel(0, imx->mmio_base + MX3_PWMCR); clk_disable_unprepare(imx->clk_per); } return 0; } static const struct pwm_ops imx_pwm_ops_v1 = { .enable = imx_pwm_enable_v1, .disable = imx_pwm_disable_v1, .config = imx_pwm_config_v1, .owner = THIS_MODULE, }; static const struct pwm_ops imx_pwm_ops_v2 = { .apply = imx_pwm_apply_v2, .owner = THIS_MODULE, }; struct imx_pwm_data { bool polarity_supported; const struct pwm_ops *ops; }; static struct imx_pwm_data imx_pwm_data_v1 = { .ops = &imx_pwm_ops_v1, }; static struct imx_pwm_data imx_pwm_data_v2 = { .polarity_supported = true, .ops = &imx_pwm_ops_v2, }; static const struct of_device_id imx_pwm_dt_ids[] = { { .compatible = "fsl,imx1-pwm", .data = &imx_pwm_data_v1, }, { .compatible = "fsl,imx27-pwm", .data = &imx_pwm_data_v2, }, { /* sentinel */ } }; MODULE_DEVICE_TABLE(of, imx_pwm_dt_ids); static int imx_pwm_probe(struct platform_device *pdev) { const struct of_device_id *of_id = of_match_device(imx_pwm_dt_ids, &pdev->dev); const struct imx_pwm_data *data; struct imx_chip *imx; struct resource *r; int ret = 0; if (!of_id) return -ENODEV; data = of_id->data; imx = devm_kzalloc(&pdev->dev, sizeof(*imx), GFP_KERNEL); if (imx == NULL) return -ENOMEM; imx->clk_per = devm_clk_get(&pdev->dev, "per"); if (IS_ERR(imx->clk_per)) { dev_err(&pdev->dev, "getting per clock failed with %ld\n", PTR_ERR(imx->clk_per)); return PTR_ERR(imx->clk_per); } imx->chip.ops = data->ops; imx->chip.dev = &pdev->dev; imx->chip.base = -1; imx->chip.npwm = 1; if (data->polarity_supported) { dev_dbg(&pdev->dev, "PWM supports output inversion\n"); imx->chip.of_xlate = of_pwm_xlate_with_flags; imx->chip.of_pwm_n_cells = 3; } r = platform_get_resource(pdev, IORESOURCE_MEM, 0); imx->mmio_base = devm_ioremap_resource(&pdev->dev, r); if (IS_ERR(imx->mmio_base)) return PTR_ERR(imx->mmio_base); ret = pwmchip_add(&imx->chip); if (ret < 0) return ret; platform_set_drvdata(pdev, imx); return 0; } static int imx_pwm_remove(struct platform_device *pdev) { struct imx_chip *imx; imx = platform_get_drvdata(pdev); if (imx == NULL) return -ENODEV; return pwmchip_remove(&imx->chip); } static struct platform_driver imx_pwm_driver = { .driver = { .name = "imx-pwm", .of_match_table = imx_pwm_dt_ids, }, .probe = imx_pwm_probe, .remove = imx_pwm_remove, }; module_platform_driver(imx_pwm_driver); MODULE_LICENSE("GPL v2"); MODULE_AUTHOR("Sascha Hauer ");