1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Expose a PWM controlled by the ChromeOS EC to the host processor. 4 * 5 * Copyright (C) 2016 Google, Inc. 6 */ 7 8 #include <linux/module.h> 9 #include <linux/platform_data/cros_ec_commands.h> 10 #include <linux/platform_data/cros_ec_proto.h> 11 #include <linux/platform_device.h> 12 #include <linux/pwm.h> 13 #include <linux/slab.h> 14 15 /** 16 * struct cros_ec_pwm_device - Driver data for EC PWM 17 * 18 * @dev: Device node 19 * @ec: Pointer to EC device 20 * @chip: PWM controller chip 21 */ 22 struct cros_ec_pwm_device { 23 struct device *dev; 24 struct cros_ec_device *ec; 25 struct pwm_chip chip; 26 }; 27 28 /** 29 * struct cros_ec_pwm - per-PWM driver data 30 * @duty_cycle: cached duty cycle 31 */ 32 struct cros_ec_pwm { 33 u16 duty_cycle; 34 }; 35 36 static inline struct cros_ec_pwm_device *pwm_to_cros_ec_pwm(struct pwm_chip *c) 37 { 38 return container_of(c, struct cros_ec_pwm_device, chip); 39 } 40 41 static int cros_ec_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm) 42 { 43 struct cros_ec_pwm *channel; 44 45 channel = kzalloc(sizeof(*channel), GFP_KERNEL); 46 if (!channel) 47 return -ENOMEM; 48 49 pwm_set_chip_data(pwm, channel); 50 51 return 0; 52 } 53 54 static void cros_ec_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm) 55 { 56 struct cros_ec_pwm *channel = pwm_get_chip_data(pwm); 57 58 kfree(channel); 59 } 60 61 static int cros_ec_pwm_set_duty(struct cros_ec_device *ec, u8 index, u16 duty) 62 { 63 struct { 64 struct cros_ec_command msg; 65 struct ec_params_pwm_set_duty params; 66 } __packed buf; 67 struct ec_params_pwm_set_duty *params = &buf.params; 68 struct cros_ec_command *msg = &buf.msg; 69 70 memset(&buf, 0, sizeof(buf)); 71 72 msg->version = 0; 73 msg->command = EC_CMD_PWM_SET_DUTY; 74 msg->insize = 0; 75 msg->outsize = sizeof(*params); 76 77 params->duty = duty; 78 params->pwm_type = EC_PWM_TYPE_GENERIC; 79 params->index = index; 80 81 return cros_ec_cmd_xfer_status(ec, msg); 82 } 83 84 static int __cros_ec_pwm_get_duty(struct cros_ec_device *ec, u8 index, 85 u32 *result) 86 { 87 struct { 88 struct cros_ec_command msg; 89 union { 90 struct ec_params_pwm_get_duty params; 91 struct ec_response_pwm_get_duty resp; 92 }; 93 } __packed buf; 94 struct ec_params_pwm_get_duty *params = &buf.params; 95 struct ec_response_pwm_get_duty *resp = &buf.resp; 96 struct cros_ec_command *msg = &buf.msg; 97 int ret; 98 99 memset(&buf, 0, sizeof(buf)); 100 101 msg->version = 0; 102 msg->command = EC_CMD_PWM_GET_DUTY; 103 msg->insize = sizeof(*resp); 104 msg->outsize = sizeof(*params); 105 106 params->pwm_type = EC_PWM_TYPE_GENERIC; 107 params->index = index; 108 109 ret = cros_ec_cmd_xfer_status(ec, msg); 110 if (result) 111 *result = msg->result; 112 if (ret < 0) 113 return ret; 114 115 return resp->duty; 116 } 117 118 static int cros_ec_pwm_get_duty(struct cros_ec_device *ec, u8 index) 119 { 120 return __cros_ec_pwm_get_duty(ec, index, NULL); 121 } 122 123 static int cros_ec_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, 124 const struct pwm_state *state) 125 { 126 struct cros_ec_pwm_device *ec_pwm = pwm_to_cros_ec_pwm(chip); 127 struct cros_ec_pwm *channel = pwm_get_chip_data(pwm); 128 u16 duty_cycle; 129 int ret; 130 131 /* The EC won't let us change the period */ 132 if (state->period != EC_PWM_MAX_DUTY) 133 return -EINVAL; 134 135 /* 136 * EC doesn't separate the concept of duty cycle and enabled, but 137 * kernel does. Translate. 138 */ 139 duty_cycle = state->enabled ? state->duty_cycle : 0; 140 141 ret = cros_ec_pwm_set_duty(ec_pwm->ec, pwm->hwpwm, duty_cycle); 142 if (ret < 0) 143 return ret; 144 145 channel->duty_cycle = state->duty_cycle; 146 147 return 0; 148 } 149 150 static void cros_ec_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm, 151 struct pwm_state *state) 152 { 153 struct cros_ec_pwm_device *ec_pwm = pwm_to_cros_ec_pwm(chip); 154 struct cros_ec_pwm *channel = pwm_get_chip_data(pwm); 155 int ret; 156 157 ret = cros_ec_pwm_get_duty(ec_pwm->ec, pwm->hwpwm); 158 if (ret < 0) { 159 dev_err(chip->dev, "error getting initial duty: %d\n", ret); 160 return; 161 } 162 163 state->enabled = (ret > 0); 164 state->period = EC_PWM_MAX_DUTY; 165 166 /* 167 * Note that "disabled" and "duty cycle == 0" are treated the same. If 168 * the cached duty cycle is not zero, used the cached duty cycle. This 169 * ensures that the configured duty cycle is kept across a disable and 170 * enable operation and avoids potentially confusing consumers. 171 * 172 * For the case of the initial hardware readout, channel->duty_cycle 173 * will be 0 and the actual duty cycle read from the EC is used. 174 */ 175 if (ret == 0 && channel->duty_cycle > 0) 176 state->duty_cycle = channel->duty_cycle; 177 else 178 state->duty_cycle = ret; 179 } 180 181 static struct pwm_device * 182 cros_ec_pwm_xlate(struct pwm_chip *pc, const struct of_phandle_args *args) 183 { 184 struct pwm_device *pwm; 185 186 if (args->args[0] >= pc->npwm) 187 return ERR_PTR(-EINVAL); 188 189 pwm = pwm_request_from_chip(pc, args->args[0], NULL); 190 if (IS_ERR(pwm)) 191 return pwm; 192 193 /* The EC won't let us change the period */ 194 pwm->args.period = EC_PWM_MAX_DUTY; 195 196 return pwm; 197 } 198 199 static const struct pwm_ops cros_ec_pwm_ops = { 200 .request = cros_ec_pwm_request, 201 .free = cros_ec_pwm_free, 202 .get_state = cros_ec_pwm_get_state, 203 .apply = cros_ec_pwm_apply, 204 .owner = THIS_MODULE, 205 }; 206 207 static int cros_ec_num_pwms(struct cros_ec_device *ec) 208 { 209 int i, ret; 210 211 /* The index field is only 8 bits */ 212 for (i = 0; i <= U8_MAX; i++) { 213 u32 result = 0; 214 215 ret = __cros_ec_pwm_get_duty(ec, i, &result); 216 /* We want to parse EC protocol errors */ 217 if (ret < 0 && !(ret == -EPROTO && result)) 218 return ret; 219 220 /* 221 * We look for SUCCESS, INVALID_COMMAND, or INVALID_PARAM 222 * responses; everything else is treated as an error. 223 */ 224 if (result == EC_RES_INVALID_COMMAND) 225 return -ENODEV; 226 else if (result == EC_RES_INVALID_PARAM) 227 return i; 228 else if (result) 229 return -EPROTO; 230 } 231 232 return U8_MAX; 233 } 234 235 static int cros_ec_pwm_probe(struct platform_device *pdev) 236 { 237 struct cros_ec_device *ec = dev_get_drvdata(pdev->dev.parent); 238 struct device *dev = &pdev->dev; 239 struct cros_ec_pwm_device *ec_pwm; 240 struct pwm_chip *chip; 241 int ret; 242 243 if (!ec) { 244 dev_err(dev, "no parent EC device\n"); 245 return -EINVAL; 246 } 247 248 ec_pwm = devm_kzalloc(dev, sizeof(*ec_pwm), GFP_KERNEL); 249 if (!ec_pwm) 250 return -ENOMEM; 251 chip = &ec_pwm->chip; 252 ec_pwm->ec = ec; 253 254 /* PWM chip */ 255 chip->dev = dev; 256 chip->ops = &cros_ec_pwm_ops; 257 chip->of_xlate = cros_ec_pwm_xlate; 258 chip->of_pwm_n_cells = 1; 259 chip->base = -1; 260 ret = cros_ec_num_pwms(ec); 261 if (ret < 0) { 262 dev_err(dev, "Couldn't find PWMs: %d\n", ret); 263 return ret; 264 } 265 chip->npwm = ret; 266 dev_dbg(dev, "Probed %u PWMs\n", chip->npwm); 267 268 ret = pwmchip_add(chip); 269 if (ret < 0) { 270 dev_err(dev, "cannot register PWM: %d\n", ret); 271 return ret; 272 } 273 274 platform_set_drvdata(pdev, ec_pwm); 275 276 return ret; 277 } 278 279 static int cros_ec_pwm_remove(struct platform_device *dev) 280 { 281 struct cros_ec_pwm_device *ec_pwm = platform_get_drvdata(dev); 282 struct pwm_chip *chip = &ec_pwm->chip; 283 284 return pwmchip_remove(chip); 285 } 286 287 #ifdef CONFIG_OF 288 static const struct of_device_id cros_ec_pwm_of_match[] = { 289 { .compatible = "google,cros-ec-pwm" }, 290 {}, 291 }; 292 MODULE_DEVICE_TABLE(of, cros_ec_pwm_of_match); 293 #endif 294 295 static struct platform_driver cros_ec_pwm_driver = { 296 .probe = cros_ec_pwm_probe, 297 .remove = cros_ec_pwm_remove, 298 .driver = { 299 .name = "cros-ec-pwm", 300 .of_match_table = of_match_ptr(cros_ec_pwm_of_match), 301 }, 302 }; 303 module_platform_driver(cros_ec_pwm_driver); 304 305 MODULE_ALIAS("platform:cros-ec-pwm"); 306 MODULE_DESCRIPTION("ChromeOS EC PWM driver"); 307 MODULE_LICENSE("GPL v2"); 308