diff options
| author | Jonathan Herman <hermanjl@cs.unc.edu> | 2013-01-22 10:38:37 -0500 |
|---|---|---|
| committer | Jonathan Herman <hermanjl@cs.unc.edu> | 2013-01-22 10:38:37 -0500 |
| commit | fcc9d2e5a6c89d22b8b773a64fb4ad21ac318446 (patch) | |
| tree | a57612d1888735a2ec7972891b68c1ac5ec8faea /arch/arm/plat-pxa/pwm.c | |
| parent | 8dea78da5cee153b8af9c07a2745f6c55057fe12 (diff) | |
Diffstat (limited to 'arch/arm/plat-pxa/pwm.c')
| -rw-r--r-- | arch/arm/plat-pxa/pwm.c | 304 |
1 files changed, 304 insertions, 0 deletions
diff --git a/arch/arm/plat-pxa/pwm.c b/arch/arm/plat-pxa/pwm.c new file mode 100644 index 00000000000..ef32686feef --- /dev/null +++ b/arch/arm/plat-pxa/pwm.c | |||
| @@ -0,0 +1,304 @@ | |||
| 1 | /* | ||
| 2 | * linux/arch/arm/mach-pxa/pwm.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 pwm_device { | ||
| 47 | struct list_head node; | ||
| 48 | struct pwm_device *secondary; | ||
| 49 | struct platform_device *pdev; | ||
| 50 | |||
| 51 | const char *label; | ||
| 52 | struct clk *clk; | ||
| 53 | int clk_enabled; | ||
| 54 | void __iomem *mmio_base; | ||
| 55 | |||
| 56 | unsigned int use_count; | ||
| 57 | unsigned int pwm_id; | ||
| 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 | int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns) | ||
| 65 | { | ||
| 66 | unsigned long long c; | ||
| 67 | unsigned long period_cycles, prescale, pv, dc; | ||
| 68 | |||
| 69 | if (pwm == NULL || period_ns == 0 || duty_ns > period_ns) | ||
| 70 | return -EINVAL; | ||
| 71 | |||
| 72 | c = clk_get_rate(pwm->clk); | ||
| 73 | c = c * period_ns; | ||
| 74 | do_div(c, 1000000000); | ||
| 75 | period_cycles = c; | ||
| 76 | |||
| 77 | if (period_cycles < 1) | ||
| 78 | period_cycles = 1; | ||
| 79 | prescale = (period_cycles - 1) / 1024; | ||
| 80 | pv = period_cycles / (prescale + 1) - 1; | ||
| 81 | |||
| 82 | if (prescale > 63) | ||
| 83 | return -EINVAL; | ||
| 84 | |||
| 85 | if (duty_ns == period_ns) | ||
| 86 | dc = PWMDCR_FD; | ||
| 87 | else | ||
| 88 | dc = (pv + 1) * duty_ns / period_ns; | ||
| 89 | |||
| 90 | /* NOTE: the clock to PWM has to be enabled first | ||
| 91 | * before writing to the registers | ||
| 92 | */ | ||
| 93 | clk_enable(pwm->clk); | ||
| 94 | __raw_writel(prescale, pwm->mmio_base + PWMCR); | ||
| 95 | __raw_writel(dc, pwm->mmio_base + PWMDCR); | ||
| 96 | __raw_writel(pv, pwm->mmio_base + PWMPCR); | ||
| 97 | clk_disable(pwm->clk); | ||
| 98 | |||
| 99 | return 0; | ||
| 100 | } | ||
| 101 | EXPORT_SYMBOL(pwm_config); | ||
| 102 | |||
| 103 | int pwm_enable(struct pwm_device *pwm) | ||
| 104 | { | ||
| 105 | int rc = 0; | ||
| 106 | |||
| 107 | if (!pwm->clk_enabled) { | ||
| 108 | rc = clk_enable(pwm->clk); | ||
| 109 | if (!rc) | ||
| 110 | pwm->clk_enabled = 1; | ||
| 111 | } | ||
| 112 | return rc; | ||
| 113 | } | ||
| 114 | EXPORT_SYMBOL(pwm_enable); | ||
| 115 | |||
| 116 | void pwm_disable(struct pwm_device *pwm) | ||
| 117 | { | ||
| 118 | if (pwm->clk_enabled) { | ||
| 119 | clk_disable(pwm->clk); | ||
| 120 | pwm->clk_enabled = 0; | ||
| 121 | } | ||
| 122 | } | ||
| 123 | EXPORT_SYMBOL(pwm_disable); | ||
| 124 | |||
| 125 | static DEFINE_MUTEX(pwm_lock); | ||
| 126 | static LIST_HEAD(pwm_list); | ||
| 127 | |||
| 128 | struct pwm_device *pwm_request(int pwm_id, const char *label) | ||
| 129 | { | ||
| 130 | struct pwm_device *pwm; | ||
| 131 | int found = 0; | ||
| 132 | |||
| 133 | mutex_lock(&pwm_lock); | ||
| 134 | |||
| 135 | list_for_each_entry(pwm, &pwm_list, node) { | ||
| 136 | if (pwm->pwm_id == pwm_id) { | ||
| 137 | found = 1; | ||
| 138 | break; | ||
| 139 | } | ||
| 140 | } | ||
| 141 | |||
| 142 | if (found) { | ||
| 143 | if (pwm->use_count == 0) { | ||
| 144 | pwm->use_count++; | ||
| 145 | pwm->label = label; | ||
| 146 | } else | ||
| 147 | pwm = ERR_PTR(-EBUSY); | ||
| 148 | } else | ||
| 149 | pwm = ERR_PTR(-ENOENT); | ||
| 150 | |||
| 151 | mutex_unlock(&pwm_lock); | ||
| 152 | return pwm; | ||
| 153 | } | ||
| 154 | EXPORT_SYMBOL(pwm_request); | ||
| 155 | |||
| 156 | void pwm_free(struct pwm_device *pwm) | ||
| 157 | { | ||
| 158 | mutex_lock(&pwm_lock); | ||
| 159 | |||
| 160 | if (pwm->use_count) { | ||
| 161 | pwm->use_count--; | ||
| 162 | pwm->label = NULL; | ||
| 163 | } else | ||
| 164 | pr_warning("PWM device already freed\n"); | ||
| 165 | |||
| 166 | mutex_unlock(&pwm_lock); | ||
| 167 | } | ||
| 168 | EXPORT_SYMBOL(pwm_free); | ||
| 169 | |||
| 170 | static inline void __add_pwm(struct pwm_device *pwm) | ||
| 171 | { | ||
| 172 | mutex_lock(&pwm_lock); | ||
| 173 | list_add_tail(&pwm->node, &pwm_list); | ||
| 174 | mutex_unlock(&pwm_lock); | ||
| 175 | } | ||
| 176 | |||
| 177 | static int __devinit pwm_probe(struct platform_device *pdev) | ||
| 178 | { | ||
| 179 | const struct platform_device_id *id = platform_get_device_id(pdev); | ||
| 180 | struct pwm_device *pwm, *secondary = NULL; | ||
| 181 | struct resource *r; | ||
| 182 | int ret = 0; | ||
| 183 | |||
| 184 | pwm = kzalloc(sizeof(struct pwm_device), GFP_KERNEL); | ||
| 185 | if (pwm == NULL) { | ||
| 186 | dev_err(&pdev->dev, "failed to allocate memory\n"); | ||
| 187 | return -ENOMEM; | ||
| 188 | } | ||
| 189 | |||
| 190 | pwm->clk = clk_get(&pdev->dev, NULL); | ||
| 191 | if (IS_ERR(pwm->clk)) { | ||
| 192 | ret = PTR_ERR(pwm->clk); | ||
| 193 | goto err_free; | ||
| 194 | } | ||
| 195 | pwm->clk_enabled = 0; | ||
| 196 | |||
| 197 | pwm->use_count = 0; | ||
| 198 | pwm->pwm_id = PWM_ID_BASE(id->driver_data) + pdev->id; | ||
| 199 | pwm->pdev = pdev; | ||
| 200 | |||
| 201 | r = platform_get_resource(pdev, IORESOURCE_MEM, 0); | ||
| 202 | if (r == NULL) { | ||
| 203 | dev_err(&pdev->dev, "no memory resource defined\n"); | ||
| 204 | ret = -ENODEV; | ||
| 205 | goto err_free_clk; | ||
| 206 | } | ||
| 207 | |||
| 208 | r = request_mem_region(r->start, resource_size(r), pdev->name); | ||
| 209 | if (r == NULL) { | ||
| 210 | dev_err(&pdev->dev, "failed to request memory resource\n"); | ||
| 211 | ret = -EBUSY; | ||
| 212 | goto err_free_clk; | ||
| 213 | } | ||
| 214 | |||
| 215 | pwm->mmio_base = ioremap(r->start, resource_size(r)); | ||
| 216 | if (pwm->mmio_base == NULL) { | ||
| 217 | dev_err(&pdev->dev, "failed to ioremap() registers\n"); | ||
| 218 | ret = -ENODEV; | ||
| 219 | goto err_free_mem; | ||
| 220 | } | ||
| 221 | |||
| 222 | if (id->driver_data & HAS_SECONDARY_PWM) { | ||
| 223 | secondary = kzalloc(sizeof(struct pwm_device), GFP_KERNEL); | ||
| 224 | if (secondary == NULL) { | ||
| 225 | ret = -ENOMEM; | ||
| 226 | goto err_free_mem; | ||
| 227 | } | ||
| 228 | |||
| 229 | *secondary = *pwm; | ||
| 230 | pwm->secondary = secondary; | ||
| 231 | |||
| 232 | /* registers for the second PWM has offset of 0x10 */ | ||
| 233 | secondary->mmio_base = pwm->mmio_base + 0x10; | ||
| 234 | secondary->pwm_id = pdev->id + 2; | ||
| 235 | } | ||
| 236 | |||
| 237 | __add_pwm(pwm); | ||
| 238 | if (secondary) | ||
| 239 | __add_pwm(secondary); | ||
| 240 | |||
| 241 | platform_set_drvdata(pdev, pwm); | ||
| 242 | return 0; | ||
| 243 | |||
| 244 | err_free_mem: | ||
| 245 | release_mem_region(r->start, resource_size(r)); | ||
| 246 | err_free_clk: | ||
| 247 | clk_put(pwm->clk); | ||
| 248 | err_free: | ||
| 249 | kfree(pwm); | ||
| 250 | return ret; | ||
| 251 | } | ||
| 252 | |||
| 253 | static int __devexit pwm_remove(struct platform_device *pdev) | ||
| 254 | { | ||
| 255 | struct pwm_device *pwm; | ||
| 256 | struct resource *r; | ||
| 257 | |||
| 258 | pwm = platform_get_drvdata(pdev); | ||
| 259 | if (pwm == NULL) | ||
| 260 | return -ENODEV; | ||
| 261 | |||
| 262 | mutex_lock(&pwm_lock); | ||
| 263 | |||
| 264 | if (pwm->secondary) { | ||
| 265 | list_del(&pwm->secondary->node); | ||
| 266 | kfree(pwm->secondary); | ||
| 267 | } | ||
| 268 | |||
| 269 | list_del(&pwm->node); | ||
| 270 | mutex_unlock(&pwm_lock); | ||
| 271 | |||
| 272 | iounmap(pwm->mmio_base); | ||
| 273 | |||
| 274 | r = platform_get_resource(pdev, IORESOURCE_MEM, 0); | ||
| 275 | release_mem_region(r->start, resource_size(r)); | ||
| 276 | |||
| 277 | clk_put(pwm->clk); | ||
| 278 | kfree(pwm); | ||
| 279 | return 0; | ||
| 280 | } | ||
| 281 | |||
| 282 | static struct platform_driver pwm_driver = { | ||
| 283 | .driver = { | ||
| 284 | .name = "pxa25x-pwm", | ||
| 285 | .owner = THIS_MODULE, | ||
| 286 | }, | ||
| 287 | .probe = pwm_probe, | ||
| 288 | .remove = __devexit_p(pwm_remove), | ||
| 289 | .id_table = pwm_id_table, | ||
| 290 | }; | ||
| 291 | |||
| 292 | static int __init pwm_init(void) | ||
| 293 | { | ||
| 294 | return platform_driver_register(&pwm_driver); | ||
| 295 | } | ||
| 296 | arch_initcall(pwm_init); | ||
| 297 | |||
| 298 | static void __exit pwm_exit(void) | ||
| 299 | { | ||
| 300 | platform_driver_unregister(&pwm_driver); | ||
| 301 | } | ||
| 302 | module_exit(pwm_exit); | ||
| 303 | |||
| 304 | MODULE_LICENSE("GPL v2"); | ||
