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 BIT(31) 28 29 #define to_lpc32xx_pwm_chip(_chip) \ 30 container_of(_chip, struct lpc32xx_pwm_chip, chip) 31 32 static int lpc32xx_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm, 33 int duty_ns, int period_ns) 34 { 35 struct lpc32xx_pwm_chip *lpc32xx = to_lpc32xx_pwm_chip(chip); 36 unsigned long long c; 37 int period_cycles, duty_cycles; 38 u32 val; 39 c = clk_get_rate(lpc32xx->clk); 40 41 /* The highest acceptable divisor is 256, which is represented by 0 */ 42 period_cycles = div64_u64(c * period_ns, 43 (unsigned long long)NSEC_PER_SEC * 256); 44 if (!period_cycles || period_cycles > 256) 45 return -ERANGE; 46 if (period_cycles == 256) 47 period_cycles = 0; 48 49 /* Compute 256 x #duty/period value and care for corner cases */ 50 duty_cycles = div64_u64((unsigned long long)(period_ns - duty_ns) * 256, 51 period_ns); 52 if (!duty_cycles) 53 duty_cycles = 1; 54 if (duty_cycles > 255) 55 duty_cycles = 255; 56 57 val = readl(lpc32xx->base + (pwm->hwpwm << 2)); 58 val &= ~0xFFFF; 59 val |= (period_cycles << 8) | duty_cycles; 60 writel(val, lpc32xx->base + (pwm->hwpwm << 2)); 61 62 return 0; 63 } 64 65 static int lpc32xx_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm) 66 { 67 struct lpc32xx_pwm_chip *lpc32xx = to_lpc32xx_pwm_chip(chip); 68 u32 val; 69 int ret; 70 71 ret = clk_prepare_enable(lpc32xx->clk); 72 if (ret) 73 return ret; 74 75 val = readl(lpc32xx->base + (pwm->hwpwm << 2)); 76 val |= PWM_ENABLE; 77 writel(val, lpc32xx->base + (pwm->hwpwm << 2)); 78 79 return 0; 80 } 81 82 static void lpc32xx_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm) 83 { 84 struct lpc32xx_pwm_chip *lpc32xx = to_lpc32xx_pwm_chip(chip); 85 u32 val; 86 87 val = readl(lpc32xx->base + (pwm->hwpwm << 2)); 88 val &= ~PWM_ENABLE; 89 writel(val, lpc32xx->base + (pwm->hwpwm << 2)); 90 91 clk_disable_unprepare(lpc32xx->clk); 92 } 93 94 static const struct pwm_ops lpc32xx_pwm_ops = { 95 .config = lpc32xx_pwm_config, 96 .enable = lpc32xx_pwm_enable, 97 .disable = lpc32xx_pwm_disable, 98 .owner = THIS_MODULE, 99 }; 100 101 static int lpc32xx_pwm_probe(struct platform_device *pdev) 102 { 103 struct lpc32xx_pwm_chip *lpc32xx; 104 struct resource *res; 105 int ret; 106 107 lpc32xx = devm_kzalloc(&pdev->dev, sizeof(*lpc32xx), GFP_KERNEL); 108 if (!lpc32xx) 109 return -ENOMEM; 110 111 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 112 lpc32xx->base = devm_ioremap_resource(&pdev->dev, res); 113 if (IS_ERR(lpc32xx->base)) 114 return PTR_ERR(lpc32xx->base); 115 116 lpc32xx->clk = devm_clk_get(&pdev->dev, NULL); 117 if (IS_ERR(lpc32xx->clk)) 118 return PTR_ERR(lpc32xx->clk); 119 120 lpc32xx->chip.dev = &pdev->dev; 121 lpc32xx->chip.ops = &lpc32xx_pwm_ops; 122 lpc32xx->chip.npwm = 1; 123 lpc32xx->chip.base = -1; 124 125 ret = pwmchip_add(&lpc32xx->chip); 126 if (ret < 0) { 127 dev_err(&pdev->dev, "failed to add PWM chip, error %d\n", ret); 128 return ret; 129 } 130 131 platform_set_drvdata(pdev, lpc32xx); 132 133 return 0; 134 } 135 136 static int lpc32xx_pwm_remove(struct platform_device *pdev) 137 { 138 struct lpc32xx_pwm_chip *lpc32xx = platform_get_drvdata(pdev); 139 unsigned int i; 140 141 for (i = 0; i < lpc32xx->chip.npwm; i++) 142 pwm_disable(&lpc32xx->chip.pwms[i]); 143 144 return pwmchip_remove(&lpc32xx->chip); 145 } 146 147 static const struct of_device_id lpc32xx_pwm_dt_ids[] = { 148 { .compatible = "nxp,lpc3220-pwm", }, 149 { /* sentinel */ } 150 }; 151 MODULE_DEVICE_TABLE(of, lpc32xx_pwm_dt_ids); 152 153 static struct platform_driver lpc32xx_pwm_driver = { 154 .driver = { 155 .name = "lpc32xx-pwm", 156 .of_match_table = lpc32xx_pwm_dt_ids, 157 }, 158 .probe = lpc32xx_pwm_probe, 159 .remove = lpc32xx_pwm_remove, 160 }; 161 module_platform_driver(lpc32xx_pwm_driver); 162 163 MODULE_ALIAS("platform:lpc32xx-pwm"); 164 MODULE_AUTHOR("Alexandre Pereira da Silva <aletes.xgr@gmail.com>"); 165 MODULE_DESCRIPTION("LPC32XX PWM Driver"); 166 MODULE_LICENSE("GPL v2"); 167