1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * simple driver for PWM (Pulse Width Modulator) controller 4 * 5 * Derived from pxa PWM driver by eric miao <eric.miao@marvell.com> 6 */ 7 8 #include <linux/bitfield.h> 9 #include <linux/bitops.h> 10 #include <linux/clk.h> 11 #include <linux/delay.h> 12 #include <linux/err.h> 13 #include <linux/io.h> 14 #include <linux/kernel.h> 15 #include <linux/module.h> 16 #include <linux/of.h> 17 #include <linux/of_device.h> 18 #include <linux/platform_device.h> 19 #include <linux/pwm.h> 20 #include <linux/slab.h> 21 22 #define MX1_PWMC 0x00 /* PWM Control Register */ 23 #define MX1_PWMS 0x04 /* PWM Sample Register */ 24 #define MX1_PWMP 0x08 /* PWM Period Register */ 25 26 #define MX1_PWMC_EN BIT(4) 27 28 struct pwm_imx1_chip { 29 struct clk *clk_ipg; 30 struct clk *clk_per; 31 void __iomem *mmio_base; 32 struct pwm_chip chip; 33 }; 34 35 #define to_pwm_imx1_chip(chip) container_of(chip, struct pwm_imx1_chip, chip) 36 37 static int pwm_imx1_clk_prepare_enable(struct pwm_chip *chip) 38 { 39 struct pwm_imx1_chip *imx = to_pwm_imx1_chip(chip); 40 int ret; 41 42 ret = clk_prepare_enable(imx->clk_ipg); 43 if (ret) 44 return ret; 45 46 ret = clk_prepare_enable(imx->clk_per); 47 if (ret) { 48 clk_disable_unprepare(imx->clk_ipg); 49 return ret; 50 } 51 52 return 0; 53 } 54 55 static void pwm_imx1_clk_disable_unprepare(struct pwm_chip *chip) 56 { 57 struct pwm_imx1_chip *imx = to_pwm_imx1_chip(chip); 58 59 clk_disable_unprepare(imx->clk_per); 60 clk_disable_unprepare(imx->clk_ipg); 61 } 62 63 static int pwm_imx1_config(struct pwm_chip *chip, 64 struct pwm_device *pwm, int duty_ns, int period_ns) 65 { 66 struct pwm_imx1_chip *imx = to_pwm_imx1_chip(chip); 67 u32 max, p; 68 69 /* 70 * The PWM subsystem allows for exact frequencies. However, 71 * I cannot connect a scope on my device to the PWM line and 72 * thus cannot provide the program the PWM controller 73 * exactly. Instead, I'm relying on the fact that the 74 * Bootloader (u-boot or WinCE+haret) has programmed the PWM 75 * function group already. So I'll just modify the PWM sample 76 * register to follow the ratio of duty_ns vs. period_ns 77 * accordingly. 78 * 79 * This is good enough for programming the brightness of 80 * the LCD backlight. 81 * 82 * The real implementation would divide PERCLK[0] first by 83 * both the prescaler (/1 .. /128) and then by CLKSEL 84 * (/2 .. /16). 85 */ 86 max = readl(imx->mmio_base + MX1_PWMP); 87 p = max * duty_ns / period_ns; 88 89 writel(max - p, imx->mmio_base + MX1_PWMS); 90 91 return 0; 92 } 93 94 static int pwm_imx1_enable(struct pwm_chip *chip, struct pwm_device *pwm) 95 { 96 struct pwm_imx1_chip *imx = to_pwm_imx1_chip(chip); 97 u32 value; 98 int ret; 99 100 ret = pwm_imx1_clk_prepare_enable(chip); 101 if (ret < 0) 102 return ret; 103 104 value = readl(imx->mmio_base + MX1_PWMC); 105 value |= MX1_PWMC_EN; 106 writel(value, imx->mmio_base + MX1_PWMC); 107 108 return 0; 109 } 110 111 static void pwm_imx1_disable(struct pwm_chip *chip, struct pwm_device *pwm) 112 { 113 struct pwm_imx1_chip *imx = to_pwm_imx1_chip(chip); 114 u32 value; 115 116 value = readl(imx->mmio_base + MX1_PWMC); 117 value &= ~MX1_PWMC_EN; 118 writel(value, imx->mmio_base + MX1_PWMC); 119 120 pwm_imx1_clk_disable_unprepare(chip); 121 } 122 123 static const struct pwm_ops pwm_imx1_ops = { 124 .enable = pwm_imx1_enable, 125 .disable = pwm_imx1_disable, 126 .config = pwm_imx1_config, 127 .owner = THIS_MODULE, 128 }; 129 130 static const struct of_device_id pwm_imx1_dt_ids[] = { 131 { .compatible = "fsl,imx1-pwm", }, 132 { /* sentinel */ } 133 }; 134 MODULE_DEVICE_TABLE(of, pwm_imx1_dt_ids); 135 136 static int pwm_imx1_probe(struct platform_device *pdev) 137 { 138 struct pwm_imx1_chip *imx; 139 struct resource *r; 140 141 imx = devm_kzalloc(&pdev->dev, sizeof(*imx), GFP_KERNEL); 142 if (!imx) 143 return -ENOMEM; 144 145 platform_set_drvdata(pdev, imx); 146 147 imx->clk_ipg = devm_clk_get(&pdev->dev, "ipg"); 148 if (IS_ERR(imx->clk_ipg)) { 149 dev_err(&pdev->dev, "getting ipg clock failed with %ld\n", 150 PTR_ERR(imx->clk_ipg)); 151 return PTR_ERR(imx->clk_ipg); 152 } 153 154 imx->clk_per = devm_clk_get(&pdev->dev, "per"); 155 if (IS_ERR(imx->clk_per)) { 156 int ret = PTR_ERR(imx->clk_per); 157 158 if (ret != -EPROBE_DEFER) 159 dev_err(&pdev->dev, 160 "failed to get peripheral clock: %d\n", 161 ret); 162 163 return ret; 164 } 165 166 imx->chip.ops = &pwm_imx1_ops; 167 imx->chip.dev = &pdev->dev; 168 imx->chip.base = -1; 169 imx->chip.npwm = 1; 170 171 r = platform_get_resource(pdev, IORESOURCE_MEM, 0); 172 imx->mmio_base = devm_ioremap_resource(&pdev->dev, r); 173 if (IS_ERR(imx->mmio_base)) 174 return PTR_ERR(imx->mmio_base); 175 176 return pwmchip_add(&imx->chip); 177 } 178 179 static int pwm_imx1_remove(struct platform_device *pdev) 180 { 181 struct pwm_imx1_chip *imx = platform_get_drvdata(pdev); 182 183 pwm_imx1_clk_disable_unprepare(&imx->chip); 184 185 return pwmchip_remove(&imx->chip); 186 } 187 188 static struct platform_driver pwm_imx1_driver = { 189 .driver = { 190 .name = "pwm-imx1", 191 .of_match_table = pwm_imx1_dt_ids, 192 }, 193 .probe = pwm_imx1_probe, 194 .remove = pwm_imx1_remove, 195 }; 196 module_platform_driver(pwm_imx1_driver); 197 198 MODULE_LICENSE("GPL v2"); 199 MODULE_AUTHOR("Sascha Hauer <s.hauer@pengutronix.de>"); 200