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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 | // SPDX-License-Identifier: GPL-2.0 /* * simple driver for PWM (Pulse Width Modulator) controller * * Derived from pxa PWM driver by eric miao <eric.miao@marvell.com> */ #include <linux/bitfield.h> #include <linux/bitops.h> #include <linux/clk.h> #include <linux/delay.h> #include <linux/err.h> #include <linux/io.h> #include <linux/kernel.h> #include <linux/module.h> #include <linux/of.h> #include <linux/of_device.h> #include <linux/platform_device.h> #include <linux/pwm.h> #include <linux/slab.h> #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 BIT(4) struct pwm_imx1_chip { struct clk *clk_ipg; struct clk *clk_per; void __iomem *mmio_base; struct pwm_chip chip; }; #define to_pwm_imx1_chip(chip) container_of(chip, struct pwm_imx1_chip, chip) static int pwm_imx1_clk_prepare_enable(struct pwm_chip *chip) { struct pwm_imx1_chip *imx = to_pwm_imx1_chip(chip); int ret; ret = clk_prepare_enable(imx->clk_ipg); if (ret) return ret; ret = clk_prepare_enable(imx->clk_per); if (ret) { clk_disable_unprepare(imx->clk_ipg); return ret; } return 0; } static void pwm_imx1_clk_disable_unprepare(struct pwm_chip *chip) { struct pwm_imx1_chip *imx = to_pwm_imx1_chip(chip); clk_disable_unprepare(imx->clk_per); clk_disable_unprepare(imx->clk_ipg); } static int pwm_imx1_config(struct pwm_chip *chip, struct pwm_device *pwm, int duty_ns, int period_ns) { struct pwm_imx1_chip *imx = to_pwm_imx1_chip(chip); u32 max, p; /* * 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). */ max = readl(imx->mmio_base + MX1_PWMP); p = max * duty_ns / period_ns; writel(max - p, imx->mmio_base + MX1_PWMS); return 0; } static int pwm_imx1_enable(struct pwm_chip *chip, struct pwm_device *pwm) { struct pwm_imx1_chip *imx = to_pwm_imx1_chip(chip); u32 value; int ret; ret = pwm_imx1_clk_prepare_enable(chip); if (ret < 0) return ret; value = readl(imx->mmio_base + MX1_PWMC); value |= MX1_PWMC_EN; writel(value, imx->mmio_base + MX1_PWMC); return 0; } static void pwm_imx1_disable(struct pwm_chip *chip, struct pwm_device *pwm) { struct pwm_imx1_chip *imx = to_pwm_imx1_chip(chip); u32 value; value = readl(imx->mmio_base + MX1_PWMC); value &= ~MX1_PWMC_EN; writel(value, imx->mmio_base + MX1_PWMC); pwm_imx1_clk_disable_unprepare(chip); } static const struct pwm_ops pwm_imx1_ops = { .enable = pwm_imx1_enable, .disable = pwm_imx1_disable, .config = pwm_imx1_config, .owner = THIS_MODULE, }; static const struct of_device_id pwm_imx1_dt_ids[] = { { .compatible = "fsl,imx1-pwm", }, { /* sentinel */ } }; MODULE_DEVICE_TABLE(of, pwm_imx1_dt_ids); static int pwm_imx1_probe(struct platform_device *pdev) { struct pwm_imx1_chip *imx; struct resource *r; imx = devm_kzalloc(&pdev->dev, sizeof(*imx), GFP_KERNEL); if (!imx) return -ENOMEM; platform_set_drvdata(pdev, imx); imx->clk_ipg = devm_clk_get(&pdev->dev, "ipg"); if (IS_ERR(imx->clk_ipg)) { dev_err(&pdev->dev, "getting ipg clock failed with %ld\n", PTR_ERR(imx->clk_ipg)); return PTR_ERR(imx->clk_ipg); } imx->clk_per = devm_clk_get(&pdev->dev, "per"); if (IS_ERR(imx->clk_per)) { int ret = PTR_ERR(imx->clk_per); if (ret != -EPROBE_DEFER) dev_err(&pdev->dev, "failed to get peripheral clock: %d\n", ret); return ret; } imx->chip.ops = &pwm_imx1_ops; imx->chip.dev = &pdev->dev; imx->chip.base = -1; imx->chip.npwm = 1; 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); return pwmchip_add(&imx->chip); } static int pwm_imx1_remove(struct platform_device *pdev) { struct pwm_imx1_chip *imx = platform_get_drvdata(pdev); pwm_imx1_clk_disable_unprepare(&imx->chip); return pwmchip_remove(&imx->chip); } static struct platform_driver pwm_imx1_driver = { .driver = { .name = "pwm-imx1", .of_match_table = pwm_imx1_dt_ids, }, .probe = pwm_imx1_probe, .remove = pwm_imx1_remove, }; module_platform_driver(pwm_imx1_driver); MODULE_LICENSE("GPL v2"); MODULE_AUTHOR("Sascha Hauer <s.hauer@pengutronix.de>"); |