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 { 86 struct { 87 struct cros_ec_command msg; 88 union { 89 struct ec_params_pwm_get_duty params; 90 struct ec_response_pwm_get_duty resp; 91 }; 92 } __packed buf; 93 struct ec_params_pwm_get_duty *params = &buf.params; 94 struct ec_response_pwm_get_duty *resp = &buf.resp; 95 struct cros_ec_command *msg = &buf.msg; 96 int ret; 97 98 memset(&buf, 0, sizeof(buf)); 99 100 msg->version = 0; 101 msg->command = EC_CMD_PWM_GET_DUTY; 102 msg->insize = sizeof(*resp); 103 msg->outsize = sizeof(*params); 104 105 params->pwm_type = EC_PWM_TYPE_GENERIC; 106 params->index = index; 107 108 ret = cros_ec_cmd_xfer_status(ec, msg); 109 if (ret < 0) 110 return ret; 111 112 return resp->duty; 113 } 114 115 static int cros_ec_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, 116 const struct pwm_state *state) 117 { 118 struct cros_ec_pwm_device *ec_pwm = pwm_to_cros_ec_pwm(chip); 119 struct cros_ec_pwm *channel = pwm_get_chip_data(pwm); 120 u16 duty_cycle; 121 int ret; 122 123 /* The EC won't let us change the period */ 124 if (state->period != EC_PWM_MAX_DUTY) 125 return -EINVAL; 126 127 if (state->polarity != PWM_POLARITY_NORMAL) 128 return -EINVAL; 129 130 /* 131 * EC doesn't separate the concept of duty cycle and enabled, but 132 * kernel does. Translate. 133 */ 134 duty_cycle = state->enabled ? state->duty_cycle : 0; 135 136 ret = cros_ec_pwm_set_duty(ec_pwm->ec, pwm->hwpwm, duty_cycle); 137 if (ret < 0) 138 return ret; 139 140 channel->duty_cycle = state->duty_cycle; 141 142 return 0; 143 } 144 145 static void cros_ec_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm, 146 struct pwm_state *state) 147 { 148 struct cros_ec_pwm_device *ec_pwm = pwm_to_cros_ec_pwm(chip); 149 struct cros_ec_pwm *channel = pwm_get_chip_data(pwm); 150 int ret; 151 152 ret = cros_ec_pwm_get_duty(ec_pwm->ec, pwm->hwpwm); 153 if (ret < 0) { 154 dev_err(chip->dev, "error getting initial duty: %d\n", ret); 155 return; 156 } 157 158 state->enabled = (ret > 0); 159 state->period = EC_PWM_MAX_DUTY; 160 161 /* 162 * Note that "disabled" and "duty cycle == 0" are treated the same. If 163 * the cached duty cycle is not zero, used the cached duty cycle. This 164 * ensures that the configured duty cycle is kept across a disable and 165 * enable operation and avoids potentially confusing consumers. 166 * 167 * For the case of the initial hardware readout, channel->duty_cycle 168 * will be 0 and the actual duty cycle read from the EC is used. 169 */ 170 if (ret == 0 && channel->duty_cycle > 0) 171 state->duty_cycle = channel->duty_cycle; 172 else 173 state->duty_cycle = ret; 174 } 175 176 static struct pwm_device * 177 cros_ec_pwm_xlate(struct pwm_chip *pc, const struct of_phandle_args *args) 178 { 179 struct pwm_device *pwm; 180 181 if (args->args[0] >= pc->npwm) 182 return ERR_PTR(-EINVAL); 183 184 pwm = pwm_request_from_chip(pc, args->args[0], NULL); 185 if (IS_ERR(pwm)) 186 return pwm; 187 188 /* The EC won't let us change the period */ 189 pwm->args.period = EC_PWM_MAX_DUTY; 190 191 return pwm; 192 } 193 194 static const struct pwm_ops cros_ec_pwm_ops = { 195 .request = cros_ec_pwm_request, 196 .free = cros_ec_pwm_free, 197 .get_state = cros_ec_pwm_get_state, 198 .apply = cros_ec_pwm_apply, 199 .owner = THIS_MODULE, 200 }; 201 202 /* 203 * Determine the number of supported PWMs. The EC does not return the number 204 * of PWMs it supports directly, so we have to read the pwm duty cycle for 205 * subsequent channels until we get an error. 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 ret = cros_ec_pwm_get_duty(ec, i); 214 /* 215 * We look for SUCCESS, INVALID_COMMAND, or INVALID_PARAM 216 * responses; everything else is treated as an error. 217 * The EC error codes map to -EOPNOTSUPP and -EINVAL, 218 * so check for those. 219 */ 220 switch (ret) { 221 case -EOPNOTSUPP: /* invalid command */ 222 return -ENODEV; 223 case -EINVAL: /* invalid parameter */ 224 return i; 225 default: 226 if (ret < 0) 227 return ret; 228 break; 229 } 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 ret = cros_ec_num_pwms(ec); 260 if (ret < 0) { 261 dev_err(dev, "Couldn't find PWMs: %d\n", ret); 262 return ret; 263 } 264 chip->npwm = ret; 265 dev_dbg(dev, "Probed %u PWMs\n", chip->npwm); 266 267 ret = pwmchip_add(chip); 268 if (ret < 0) { 269 dev_err(dev, "cannot register PWM: %d\n", ret); 270 return ret; 271 } 272 273 platform_set_drvdata(pdev, ec_pwm); 274 275 return ret; 276 } 277 278 static int cros_ec_pwm_remove(struct platform_device *dev) 279 { 280 struct cros_ec_pwm_device *ec_pwm = platform_get_drvdata(dev); 281 struct pwm_chip *chip = &ec_pwm->chip; 282 283 return pwmchip_remove(chip); 284 } 285 286 #ifdef CONFIG_OF 287 static const struct of_device_id cros_ec_pwm_of_match[] = { 288 { .compatible = "google,cros-ec-pwm" }, 289 {}, 290 }; 291 MODULE_DEVICE_TABLE(of, cros_ec_pwm_of_match); 292 #endif 293 294 static struct platform_driver cros_ec_pwm_driver = { 295 .probe = cros_ec_pwm_probe, 296 .remove = cros_ec_pwm_remove, 297 .driver = { 298 .name = "cros-ec-pwm", 299 .of_match_table = of_match_ptr(cros_ec_pwm_of_match), 300 }, 301 }; 302 module_platform_driver(cros_ec_pwm_driver); 303 304 MODULE_ALIAS("platform:cros-ec-pwm"); 305 MODULE_DESCRIPTION("ChromeOS EC PWM driver"); 306 MODULE_LICENSE("GPL v2"); 307