1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * ECAP PWM driver 4 * 5 * Copyright (C) 2012 Texas Instruments, Inc. - https://www.ti.com/ 6 */ 7 8 #include <linux/module.h> 9 #include <linux/platform_device.h> 10 #include <linux/io.h> 11 #include <linux/err.h> 12 #include <linux/clk.h> 13 #include <linux/pm_runtime.h> 14 #include <linux/pwm.h> 15 #include <linux/of.h> 16 17 /* ECAP registers and bits definitions */ 18 #define CAP1 0x08 19 #define CAP2 0x0C 20 #define CAP3 0x10 21 #define CAP4 0x14 22 #define ECCTL2 0x2A 23 #define ECCTL2_APWM_POL_LOW BIT(10) 24 #define ECCTL2_APWM_MODE BIT(9) 25 #define ECCTL2_SYNC_SEL_DISA (BIT(7) | BIT(6)) 26 #define ECCTL2_TSCTR_FREERUN BIT(4) 27 28 struct ecap_context { 29 u32 cap3; 30 u32 cap4; 31 u16 ecctl2; 32 }; 33 34 struct ecap_pwm_chip { 35 struct pwm_chip chip; 36 unsigned int clk_rate; 37 void __iomem *mmio_base; 38 struct ecap_context ctx; 39 }; 40 41 static inline struct ecap_pwm_chip *to_ecap_pwm_chip(struct pwm_chip *chip) 42 { 43 return container_of(chip, struct ecap_pwm_chip, chip); 44 } 45 46 /* 47 * period_ns = 10^9 * period_cycles / PWM_CLK_RATE 48 * duty_ns = 10^9 * duty_cycles / PWM_CLK_RATE 49 */ 50 static int ecap_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm, 51 int duty_ns, int period_ns, int enabled) 52 { 53 struct ecap_pwm_chip *pc = to_ecap_pwm_chip(chip); 54 u32 period_cycles, duty_cycles; 55 unsigned long long c; 56 u16 value; 57 58 c = pc->clk_rate; 59 c = c * period_ns; 60 do_div(c, NSEC_PER_SEC); 61 period_cycles = (u32)c; 62 63 if (period_cycles < 1) { 64 period_cycles = 1; 65 duty_cycles = 1; 66 } else { 67 c = pc->clk_rate; 68 c = c * duty_ns; 69 do_div(c, NSEC_PER_SEC); 70 duty_cycles = (u32)c; 71 } 72 73 pm_runtime_get_sync(pc->chip.dev); 74 75 value = readw(pc->mmio_base + ECCTL2); 76 77 /* Configure APWM mode & disable sync option */ 78 value |= ECCTL2_APWM_MODE | ECCTL2_SYNC_SEL_DISA; 79 80 writew(value, pc->mmio_base + ECCTL2); 81 82 if (!enabled) { 83 /* Update active registers if not running */ 84 writel(duty_cycles, pc->mmio_base + CAP2); 85 writel(period_cycles, pc->mmio_base + CAP1); 86 } else { 87 /* 88 * Update shadow registers to configure period and 89 * compare values. This helps current PWM period to 90 * complete on reconfiguring 91 */ 92 writel(duty_cycles, pc->mmio_base + CAP4); 93 writel(period_cycles, pc->mmio_base + CAP3); 94 } 95 96 if (!enabled) { 97 value = readw(pc->mmio_base + ECCTL2); 98 /* Disable APWM mode to put APWM output Low */ 99 value &= ~ECCTL2_APWM_MODE; 100 writew(value, pc->mmio_base + ECCTL2); 101 } 102 103 pm_runtime_put_sync(pc->chip.dev); 104 105 return 0; 106 } 107 108 static int ecap_pwm_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm, 109 enum pwm_polarity polarity) 110 { 111 struct ecap_pwm_chip *pc = to_ecap_pwm_chip(chip); 112 u16 value; 113 114 pm_runtime_get_sync(pc->chip.dev); 115 116 value = readw(pc->mmio_base + ECCTL2); 117 118 if (polarity == PWM_POLARITY_INVERSED) 119 /* Duty cycle defines LOW period of PWM */ 120 value |= ECCTL2_APWM_POL_LOW; 121 else 122 /* Duty cycle defines HIGH period of PWM */ 123 value &= ~ECCTL2_APWM_POL_LOW; 124 125 writew(value, pc->mmio_base + ECCTL2); 126 127 pm_runtime_put_sync(pc->chip.dev); 128 129 return 0; 130 } 131 132 static int ecap_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm) 133 { 134 struct ecap_pwm_chip *pc = to_ecap_pwm_chip(chip); 135 u16 value; 136 137 /* Leave clock enabled on enabling PWM */ 138 pm_runtime_get_sync(pc->chip.dev); 139 140 /* 141 * Enable 'Free run Time stamp counter mode' to start counter 142 * and 'APWM mode' to enable APWM output 143 */ 144 value = readw(pc->mmio_base + ECCTL2); 145 value |= ECCTL2_TSCTR_FREERUN | ECCTL2_APWM_MODE; 146 writew(value, pc->mmio_base + ECCTL2); 147 148 return 0; 149 } 150 151 static void ecap_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm) 152 { 153 struct ecap_pwm_chip *pc = to_ecap_pwm_chip(chip); 154 u16 value; 155 156 /* 157 * Disable 'Free run Time stamp counter mode' to stop counter 158 * and 'APWM mode' to put APWM output to low 159 */ 160 value = readw(pc->mmio_base + ECCTL2); 161 value &= ~(ECCTL2_TSCTR_FREERUN | ECCTL2_APWM_MODE); 162 writew(value, pc->mmio_base + ECCTL2); 163 164 /* Disable clock on PWM disable */ 165 pm_runtime_put_sync(pc->chip.dev); 166 } 167 168 static int ecap_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, 169 const struct pwm_state *state) 170 { 171 int err; 172 int enabled = pwm->state.enabled; 173 174 if (state->polarity != pwm->state.polarity) { 175 176 if (enabled) { 177 ecap_pwm_disable(chip, pwm); 178 enabled = false; 179 } 180 181 err = ecap_pwm_set_polarity(chip, pwm, state->polarity); 182 if (err) 183 return err; 184 } 185 186 if (!state->enabled) { 187 if (enabled) 188 ecap_pwm_disable(chip, pwm); 189 return 0; 190 } 191 192 if (state->period > NSEC_PER_SEC) 193 return -ERANGE; 194 195 err = ecap_pwm_config(chip, pwm, state->duty_cycle, 196 state->period, enabled); 197 if (err) 198 return err; 199 200 if (!enabled) 201 return ecap_pwm_enable(chip, pwm); 202 203 return 0; 204 } 205 206 static const struct pwm_ops ecap_pwm_ops = { 207 .apply = ecap_pwm_apply, 208 }; 209 210 static const struct of_device_id ecap_of_match[] = { 211 { .compatible = "ti,am3352-ecap" }, 212 { .compatible = "ti,am33xx-ecap" }, 213 {}, 214 }; 215 MODULE_DEVICE_TABLE(of, ecap_of_match); 216 217 static int ecap_pwm_probe(struct platform_device *pdev) 218 { 219 struct device_node *np = pdev->dev.of_node; 220 struct ecap_pwm_chip *pc; 221 struct clk *clk; 222 int ret; 223 224 pc = devm_kzalloc(&pdev->dev, sizeof(*pc), GFP_KERNEL); 225 if (!pc) 226 return -ENOMEM; 227 228 clk = devm_clk_get(&pdev->dev, "fck"); 229 if (IS_ERR(clk)) { 230 if (of_device_is_compatible(np, "ti,am33xx-ecap")) { 231 dev_warn(&pdev->dev, "Binding is obsolete.\n"); 232 clk = devm_clk_get(pdev->dev.parent, "fck"); 233 } 234 } 235 236 if (IS_ERR(clk)) { 237 dev_err(&pdev->dev, "failed to get clock\n"); 238 return PTR_ERR(clk); 239 } 240 241 pc->clk_rate = clk_get_rate(clk); 242 if (!pc->clk_rate) { 243 dev_err(&pdev->dev, "failed to get clock rate\n"); 244 return -EINVAL; 245 } 246 247 pc->chip.dev = &pdev->dev; 248 pc->chip.ops = &ecap_pwm_ops; 249 pc->chip.npwm = 1; 250 251 pc->mmio_base = devm_platform_ioremap_resource(pdev, 0); 252 if (IS_ERR(pc->mmio_base)) 253 return PTR_ERR(pc->mmio_base); 254 255 ret = devm_pwmchip_add(&pdev->dev, &pc->chip); 256 if (ret < 0) { 257 dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret); 258 return ret; 259 } 260 261 platform_set_drvdata(pdev, pc); 262 pm_runtime_enable(&pdev->dev); 263 264 return 0; 265 } 266 267 static void ecap_pwm_remove(struct platform_device *pdev) 268 { 269 pm_runtime_disable(&pdev->dev); 270 } 271 272 static void ecap_pwm_save_context(struct ecap_pwm_chip *pc) 273 { 274 pm_runtime_get_sync(pc->chip.dev); 275 pc->ctx.ecctl2 = readw(pc->mmio_base + ECCTL2); 276 pc->ctx.cap4 = readl(pc->mmio_base + CAP4); 277 pc->ctx.cap3 = readl(pc->mmio_base + CAP3); 278 pm_runtime_put_sync(pc->chip.dev); 279 } 280 281 static void ecap_pwm_restore_context(struct ecap_pwm_chip *pc) 282 { 283 writel(pc->ctx.cap3, pc->mmio_base + CAP3); 284 writel(pc->ctx.cap4, pc->mmio_base + CAP4); 285 writew(pc->ctx.ecctl2, pc->mmio_base + ECCTL2); 286 } 287 288 static int ecap_pwm_suspend(struct device *dev) 289 { 290 struct ecap_pwm_chip *pc = dev_get_drvdata(dev); 291 struct pwm_device *pwm = pc->chip.pwms; 292 293 ecap_pwm_save_context(pc); 294 295 /* Disable explicitly if PWM is running */ 296 if (pwm_is_enabled(pwm)) 297 pm_runtime_put_sync(dev); 298 299 return 0; 300 } 301 302 static int ecap_pwm_resume(struct device *dev) 303 { 304 struct ecap_pwm_chip *pc = dev_get_drvdata(dev); 305 struct pwm_device *pwm = pc->chip.pwms; 306 307 /* Enable explicitly if PWM was running */ 308 if (pwm_is_enabled(pwm)) 309 pm_runtime_get_sync(dev); 310 311 ecap_pwm_restore_context(pc); 312 return 0; 313 } 314 315 static DEFINE_SIMPLE_DEV_PM_OPS(ecap_pwm_pm_ops, ecap_pwm_suspend, ecap_pwm_resume); 316 317 static struct platform_driver ecap_pwm_driver = { 318 .driver = { 319 .name = "ecap", 320 .of_match_table = ecap_of_match, 321 .pm = pm_ptr(&ecap_pwm_pm_ops), 322 }, 323 .probe = ecap_pwm_probe, 324 .remove_new = ecap_pwm_remove, 325 }; 326 module_platform_driver(ecap_pwm_driver); 327 328 MODULE_DESCRIPTION("ECAP PWM driver"); 329 MODULE_AUTHOR("Texas Instruments"); 330 MODULE_LICENSE("GPL"); 331