1 /* 2 * Copyright 2012 Alexandre Pereira da Silva <aletes.xgr@gmail.com> 3 * 4 * This program is free software; you can redistribute it and/or modify 5 * it under the terms of the GNU General Public License as published by 6 * the Free Software Foundation; version 2. 7 * 8 */ 9 10 #include <linux/clk.h> 11 #include <linux/err.h> 12 #include <linux/io.h> 13 #include <linux/kernel.h> 14 #include <linux/module.h> 15 #include <linux/of.h> 16 #include <linux/of_address.h> 17 #include <linux/platform_device.h> 18 #include <linux/pwm.h> 19 #include <linux/slab.h> 20 21 struct lpc32xx_pwm_chip { 22 struct pwm_chip chip; 23 struct clk *clk; 24 void __iomem *base; 25 }; 26 27 #define PWM_ENABLE (1 << 31) 28 #define PWM_RELOADV(x) (((x) & 0xFF) << 8) 29 #define PWM_DUTY(x) ((x) & 0xFF) 30 31 #define to_lpc32xx_pwm_chip(_chip) \ 32 container_of(_chip, struct lpc32xx_pwm_chip, chip) 33 34 static int lpc32xx_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm, 35 int duty_ns, int period_ns) 36 { 37 struct lpc32xx_pwm_chip *lpc32xx = to_lpc32xx_pwm_chip(chip); 38 unsigned long long c; 39 int period_cycles, duty_cycles; 40 41 c = clk_get_rate(lpc32xx->clk) / 256; 42 c = c * period_ns; 43 do_div(c, NSEC_PER_SEC); 44 45 /* Handle high and low extremes */ 46 if (c == 0) 47 c = 1; 48 if (c > 255) 49 c = 0; /* 0 set division by 256 */ 50 period_cycles = c; 51 52 /* The duty-cycle value is as follows: 53 * 54 * DUTY-CYCLE HIGH LEVEL 55 * 1 99.9% 56 * 25 90.0% 57 * 128 50.0% 58 * 220 10.0% 59 * 255 0.1% 60 * 0 0.0% 61 * 62 * In other words, the register value is duty-cycle % 256 with 63 * duty-cycle in the range 1-256. 64 */ 65 c = 256 * duty_ns; 66 do_div(c, period_ns); 67 if (c > 255) 68 c = 255; 69 duty_cycles = 256 - c; 70 71 writel(PWM_ENABLE | PWM_RELOADV(period_cycles) | PWM_DUTY(duty_cycles), 72 lpc32xx->base + (pwm->hwpwm << 2)); 73 74 return 0; 75 } 76 77 static int lpc32xx_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm) 78 { 79 struct lpc32xx_pwm_chip *lpc32xx = to_lpc32xx_pwm_chip(chip); 80 81 return clk_enable(lpc32xx->clk); 82 } 83 84 static void lpc32xx_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm) 85 { 86 struct lpc32xx_pwm_chip *lpc32xx = to_lpc32xx_pwm_chip(chip); 87 88 writel(0, lpc32xx->base + (pwm->hwpwm << 2)); 89 clk_disable(lpc32xx->clk); 90 } 91 92 static const struct pwm_ops lpc32xx_pwm_ops = { 93 .config = lpc32xx_pwm_config, 94 .enable = lpc32xx_pwm_enable, 95 .disable = lpc32xx_pwm_disable, 96 .owner = THIS_MODULE, 97 }; 98 99 static int lpc32xx_pwm_probe(struct platform_device *pdev) 100 { 101 struct lpc32xx_pwm_chip *lpc32xx; 102 struct resource *res; 103 int ret; 104 105 lpc32xx = devm_kzalloc(&pdev->dev, sizeof(*lpc32xx), GFP_KERNEL); 106 if (!lpc32xx) 107 return -ENOMEM; 108 109 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 110 if (!res) 111 return -EINVAL; 112 113 lpc32xx->base = devm_request_and_ioremap(&pdev->dev, res); 114 if (!lpc32xx->base) 115 return -EADDRNOTAVAIL; 116 117 lpc32xx->clk = devm_clk_get(&pdev->dev, NULL); 118 if (IS_ERR(lpc32xx->clk)) 119 return PTR_ERR(lpc32xx->clk); 120 121 lpc32xx->chip.dev = &pdev->dev; 122 lpc32xx->chip.ops = &lpc32xx_pwm_ops; 123 lpc32xx->chip.npwm = 2; 124 lpc32xx->chip.base = -1; 125 126 ret = pwmchip_add(&lpc32xx->chip); 127 if (ret < 0) { 128 dev_err(&pdev->dev, "failed to add PWM chip, error %d\n", ret); 129 return ret; 130 } 131 132 platform_set_drvdata(pdev, lpc32xx); 133 134 return 0; 135 } 136 137 static int lpc32xx_pwm_remove(struct platform_device *pdev) 138 { 139 struct lpc32xx_pwm_chip *lpc32xx = platform_get_drvdata(pdev); 140 unsigned int i; 141 142 for (i = 0; i < lpc32xx->chip.npwm; i++) 143 pwm_disable(&lpc32xx->chip.pwms[i]); 144 145 return pwmchip_remove(&lpc32xx->chip); 146 } 147 148 static struct of_device_id lpc32xx_pwm_dt_ids[] = { 149 { .compatible = "nxp,lpc3220-pwm", }, 150 { /* sentinel */ } 151 }; 152 MODULE_DEVICE_TABLE(of, lpc32xx_pwm_dt_ids); 153 154 static struct platform_driver lpc32xx_pwm_driver = { 155 .driver = { 156 .name = "lpc32xx-pwm", 157 .of_match_table = of_match_ptr(lpc32xx_pwm_dt_ids), 158 }, 159 .probe = lpc32xx_pwm_probe, 160 .remove = lpc32xx_pwm_remove, 161 }; 162 module_platform_driver(lpc32xx_pwm_driver); 163 164 MODULE_ALIAS("platform:lpc32xx-pwm"); 165 MODULE_AUTHOR("Alexandre Pereira da Silva <aletes.xgr@gmail.com>"); 166 MODULE_DESCRIPTION("LPC32XX PWM Driver"); 167 MODULE_LICENSE("GPL v2"); 168