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| 1 | /* |
| 2 | * drivers/pwm/pwm-pxa.c |
| 3 | * |
| 4 | * simple driver for PWM (Pulse Width Modulator) controller |
| 5 | * |
| 6 | * This program is free software; you can redistribute it and/or modify |
| 7 | * it under the terms of the GNU General Public License version 2 as |
| 8 | * published by the Free Software Foundation. |
| 9 | * |
| 10 | * 2008-02-13 initial version |
| 11 | * eric miao <eric.miao@marvell.com> |
| 12 | */ |
| 13 | |
| 14 | #include <linux/module.h> |
| 15 | #include <linux/kernel.h> |
| 16 | #include <linux/platform_device.h> |
| 17 | #include <linux/slab.h> |
| 18 | #include <linux/err.h> |
| 19 | #include <linux/clk.h> |
| 20 | #include <linux/io.h> |
| 21 | #include <linux/pwm.h> |
| 22 | |
| 23 | #include <asm/div64.h> |
| 24 | |
| 25 | #define HAS_SECONDARY_PWM 0x10 |
| 26 | #define PWM_ID_BASE(d) ((d) & 0xf) |
| 27 | |
| 28 | static const struct platform_device_id pwm_id_table[] = { |
| 29 | /* PWM has_secondary_pwm? */ |
| 30 | { "pxa25x-pwm", 0 }, |
| 31 | { "pxa27x-pwm", 0 | HAS_SECONDARY_PWM }, |
| 32 | { "pxa168-pwm", 1 }, |
| 33 | { "pxa910-pwm", 1 }, |
| 34 | { }, |
| 35 | }; |
| 36 | MODULE_DEVICE_TABLE(platform, pwm_id_table); |
| 37 | |
| 38 | /* PWM registers and bits definitions */ |
| 39 | #define PWMCR (0x00) |
| 40 | #define PWMDCR (0x04) |
| 41 | #define PWMPCR (0x08) |
| 42 | |
| 43 | #define PWMCR_SD (1 << 6) |
| 44 | #define PWMDCR_FD (1 << 10) |
| 45 | |
| 46 | struct pxa_pwm_chip { |
| 47 | struct pwm_chip chip; |
| 48 | struct device *dev; |
| 49 | |
| 50 | struct clk *clk; |
| 51 | int clk_enabled; |
| 52 | void __iomem *mmio_base; |
| 53 | }; |
| 54 | |
| 55 | static inline struct pxa_pwm_chip *to_pxa_pwm_chip(struct pwm_chip *chip) |
| 56 | { |
| 57 | return container_of(chip, struct pxa_pwm_chip, chip); |
| 58 | } |
| 59 | |
| 60 | /* |
| 61 | * period_ns = 10^9 * (PRESCALE + 1) * (PV + 1) / PWM_CLK_RATE |
| 62 | * duty_ns = 10^9 * (PRESCALE + 1) * DC / PWM_CLK_RATE |
| 63 | */ |
| 64 | static int pxa_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm, |
| 65 | int duty_ns, int period_ns) |
| 66 | { |
| 67 | struct pxa_pwm_chip *pc = to_pxa_pwm_chip(chip); |
| 68 | unsigned long long c; |
| 69 | unsigned long period_cycles, prescale, pv, dc; |
| 70 | unsigned long offset; |
| 71 | int rc; |
| 72 | |
| 73 | if (period_ns == 0 || duty_ns > period_ns) |
| 74 | return -EINVAL; |
| 75 | |
| 76 | offset = pwm->hwpwm ? 0x10 : 0; |
| 77 | |
| 78 | c = clk_get_rate(pc->clk); |
| 79 | c = c * period_ns; |
| 80 | do_div(c, 1000000000); |
| 81 | period_cycles = c; |
| 82 | |
| 83 | if (period_cycles < 1) |
| 84 | period_cycles = 1; |
| 85 | prescale = (period_cycles - 1) / 1024; |
| 86 | pv = period_cycles / (prescale + 1) - 1; |
| 87 | |
| 88 | if (prescale > 63) |
| 89 | return -EINVAL; |
| 90 | |
| 91 | if (duty_ns == period_ns) |
| 92 | dc = PWMDCR_FD; |
| 93 | else |
| 94 | dc = (pv + 1) * duty_ns / period_ns; |
| 95 | |
| 96 | /* NOTE: the clock to PWM has to be enabled first |
| 97 | * before writing to the registers |
| 98 | */ |
| 99 | rc = clk_prepare_enable(pc->clk); |
| 100 | if (rc < 0) |
| 101 | return rc; |
| 102 | |
| 103 | writel(prescale, pc->mmio_base + offset + PWMCR); |
| 104 | writel(dc, pc->mmio_base + offset + PWMDCR); |
| 105 | writel(pv, pc->mmio_base + offset + PWMPCR); |
| 106 | |
| 107 | clk_disable_unprepare(pc->clk); |
| 108 | return 0; |
| 109 | } |
| 110 | |
| 111 | static int pxa_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm) |
| 112 | { |
| 113 | struct pxa_pwm_chip *pc = to_pxa_pwm_chip(chip); |
| 114 | int rc = 0; |
| 115 | |
| 116 | if (!pc->clk_enabled) { |
| 117 | rc = clk_prepare_enable(pc->clk); |
| 118 | if (!rc) |
| 119 | pc->clk_enabled++; |
| 120 | } |
| 121 | return rc; |
| 122 | } |
| 123 | |
| 124 | static void pxa_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm) |
| 125 | { |
| 126 | struct pxa_pwm_chip *pc = to_pxa_pwm_chip(chip); |
| 127 | |
| 128 | if (pc->clk_enabled) { |
| 129 | clk_disable_unprepare(pc->clk); |
| 130 | pc->clk_enabled--; |
| 131 | } |
| 132 | } |
| 133 | |
| 134 | static struct pwm_ops pxa_pwm_ops = { |
| 135 | .config = pxa_pwm_config, |
| 136 | .enable = pxa_pwm_enable, |
| 137 | .disable = pxa_pwm_disable, |
| 138 | .owner = THIS_MODULE, |
| 139 | }; |
| 140 | |
| 141 | static int __devinit pwm_probe(struct platform_device *pdev) |
| 142 | { |
| 143 | const struct platform_device_id *id = platform_get_device_id(pdev); |
| 144 | struct pxa_pwm_chip *pwm; |
| 145 | struct resource *r; |
| 146 | int ret = 0; |
| 147 | |
| 148 | pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL); |
| 149 | if (pwm == NULL) { |
| 150 | dev_err(&pdev->dev, "failed to allocate memory\n"); |
| 151 | return -ENOMEM; |
| 152 | } |
| 153 | |
| 154 | pwm->clk = devm_clk_get(&pdev->dev, NULL); |
| 155 | if (IS_ERR(pwm->clk)) |
| 156 | return PTR_ERR(pwm->clk); |
| 157 | |
| 158 | pwm->clk_enabled = 0; |
| 159 | |
| 160 | pwm->chip.dev = &pdev->dev; |
| 161 | pwm->chip.ops = &pxa_pwm_ops; |
| 162 | pwm->chip.base = -1; |
| 163 | pwm->chip.npwm = (id->driver_data & HAS_SECONDARY_PWM) ? 2 : 1; |
| 164 | |
| 165 | r = platform_get_resource(pdev, IORESOURCE_MEM, 0); |
| 166 | if (r == NULL) { |
| 167 | dev_err(&pdev->dev, "no memory resource defined\n"); |
| 168 | return -ENODEV; |
| 169 | } |
| 170 | |
| 171 | pwm->mmio_base = devm_request_and_ioremap(&pdev->dev, r); |
| 172 | if (pwm->mmio_base == NULL) |
| 173 | return -EADDRNOTAVAIL; |
| 174 | |
| 175 | ret = pwmchip_add(&pwm->chip); |
| 176 | if (ret < 0) { |
| 177 | dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret); |
| 178 | return ret; |
| 179 | } |
| 180 | |
| 181 | platform_set_drvdata(pdev, pwm); |
| 182 | return 0; |
| 183 | } |
| 184 | |
| 185 | static int __devexit pwm_remove(struct platform_device *pdev) |
| 186 | { |
| 187 | struct pxa_pwm_chip *chip; |
| 188 | |
| 189 | chip = platform_get_drvdata(pdev); |
| 190 | if (chip == NULL) |
| 191 | return -ENODEV; |
| 192 | |
| 193 | return pwmchip_remove(&chip->chip); |
| 194 | } |
| 195 | |
| 196 | static struct platform_driver pwm_driver = { |
| 197 | .driver = { |
| 198 | .name = "pxa25x-pwm", |
| 199 | .owner = THIS_MODULE, |
| 200 | }, |
| 201 | .probe = pwm_probe, |
| 202 | .remove = __devexit_p(pwm_remove), |
| 203 | .id_table = pwm_id_table, |
| 204 | }; |
| 205 | |
| 206 | static int __init pwm_init(void) |
| 207 | { |
| 208 | return platform_driver_register(&pwm_driver); |
| 209 | } |
| 210 | arch_initcall(pwm_init); |
| 211 | |
| 212 | static void __exit pwm_exit(void) |
| 213 | { |
| 214 | platform_driver_unregister(&pwm_driver); |
| 215 | } |
| 216 | module_exit(pwm_exit); |
| 217 | |
| 218 | MODULE_LICENSE("GPL v2"); |
| 219 |
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Tags:
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od-2011-09-18
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