1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * ST SPEAr ADC driver 4 * 5 * Copyright 2012 Stefan Roese <sr@denx.de> 6 */ 7 8 #include <linux/module.h> 9 #include <linux/platform_device.h> 10 #include <linux/interrupt.h> 11 #include <linux/device.h> 12 #include <linux/kernel.h> 13 #include <linux/slab.h> 14 #include <linux/io.h> 15 #include <linux/clk.h> 16 #include <linux/err.h> 17 #include <linux/completion.h> 18 #include <linux/of.h> 19 #include <linux/of_address.h> 20 21 #include <linux/iio/iio.h> 22 #include <linux/iio/sysfs.h> 23 24 /* SPEAR registers definitions */ 25 #define SPEAR600_ADC_SCAN_RATE_LO(x) ((x) & 0xFFFF) 26 #define SPEAR600_ADC_SCAN_RATE_HI(x) (((x) >> 0x10) & 0xFFFF) 27 #define SPEAR_ADC_CLK_LOW(x) (((x) & 0xf) << 0) 28 #define SPEAR_ADC_CLK_HIGH(x) (((x) & 0xf) << 4) 29 30 /* Bit definitions for SPEAR_ADC_STATUS */ 31 #define SPEAR_ADC_STATUS_START_CONVERSION BIT(0) 32 #define SPEAR_ADC_STATUS_CHANNEL_NUM(x) ((x) << 1) 33 #define SPEAR_ADC_STATUS_ADC_ENABLE BIT(4) 34 #define SPEAR_ADC_STATUS_AVG_SAMPLE(x) ((x) << 5) 35 #define SPEAR_ADC_STATUS_VREF_INTERNAL BIT(9) 36 37 #define SPEAR_ADC_DATA_MASK 0x03ff 38 #define SPEAR_ADC_DATA_BITS 10 39 40 #define SPEAR_ADC_MOD_NAME "spear-adc" 41 42 #define SPEAR_ADC_CHANNEL_NUM 8 43 44 #define SPEAR_ADC_CLK_MIN 2500000 45 #define SPEAR_ADC_CLK_MAX 20000000 46 47 struct adc_regs_spear3xx { 48 u32 status; 49 u32 average; 50 u32 scan_rate; 51 u32 clk; /* Not avail for 1340 & 1310 */ 52 u32 ch_ctrl[SPEAR_ADC_CHANNEL_NUM]; 53 u32 ch_data[SPEAR_ADC_CHANNEL_NUM]; 54 }; 55 56 struct chan_data { 57 u32 lsb; 58 u32 msb; 59 }; 60 61 struct adc_regs_spear6xx { 62 u32 status; 63 u32 pad[2]; 64 u32 clk; 65 u32 ch_ctrl[SPEAR_ADC_CHANNEL_NUM]; 66 struct chan_data ch_data[SPEAR_ADC_CHANNEL_NUM]; 67 u32 scan_rate_lo; 68 u32 scan_rate_hi; 69 struct chan_data average; 70 }; 71 72 struct spear_adc_state { 73 struct device_node *np; 74 struct adc_regs_spear3xx __iomem *adc_base_spear3xx; 75 struct adc_regs_spear6xx __iomem *adc_base_spear6xx; 76 struct clk *clk; 77 struct completion completion; 78 /* 79 * Lock to protect the device state during a potential concurrent 80 * read access from userspace. Reading a raw value requires a sequence 81 * of register writes, then a wait for a completion callback, 82 * and finally a register read, during which userspace could issue 83 * another read request. This lock protects a read access from 84 * ocurring before another one has finished. 85 */ 86 struct mutex lock; 87 u32 current_clk; 88 u32 sampling_freq; 89 u32 avg_samples; 90 u32 vref_external; 91 u32 value; 92 }; 93 94 /* 95 * Functions to access some SPEAr ADC register. Abstracted into 96 * static inline functions, because of different register offsets 97 * on different SoC variants (SPEAr300 vs SPEAr600 etc). 98 */ 99 static void spear_adc_set_status(struct spear_adc_state *st, u32 val) 100 { 101 __raw_writel(val, &st->adc_base_spear6xx->status); 102 } 103 104 static void spear_adc_set_clk(struct spear_adc_state *st, u32 val) 105 { 106 u32 clk_high, clk_low, count; 107 u32 apb_clk = clk_get_rate(st->clk); 108 109 count = DIV_ROUND_UP(apb_clk, val); 110 clk_low = count / 2; 111 clk_high = count - clk_low; 112 st->current_clk = apb_clk / count; 113 114 __raw_writel(SPEAR_ADC_CLK_LOW(clk_low) | SPEAR_ADC_CLK_HIGH(clk_high), 115 &st->adc_base_spear6xx->clk); 116 } 117 118 static void spear_adc_set_ctrl(struct spear_adc_state *st, int n, 119 u32 val) 120 { 121 __raw_writel(val, &st->adc_base_spear6xx->ch_ctrl[n]); 122 } 123 124 static u32 spear_adc_get_average(struct spear_adc_state *st) 125 { 126 if (of_device_is_compatible(st->np, "st,spear600-adc")) { 127 return __raw_readl(&st->adc_base_spear6xx->average.msb) & 128 SPEAR_ADC_DATA_MASK; 129 } else { 130 return __raw_readl(&st->adc_base_spear3xx->average) & 131 SPEAR_ADC_DATA_MASK; 132 } 133 } 134 135 static void spear_adc_set_scanrate(struct spear_adc_state *st, u32 rate) 136 { 137 if (of_device_is_compatible(st->np, "st,spear600-adc")) { 138 __raw_writel(SPEAR600_ADC_SCAN_RATE_LO(rate), 139 &st->adc_base_spear6xx->scan_rate_lo); 140 __raw_writel(SPEAR600_ADC_SCAN_RATE_HI(rate), 141 &st->adc_base_spear6xx->scan_rate_hi); 142 } else { 143 __raw_writel(rate, &st->adc_base_spear3xx->scan_rate); 144 } 145 } 146 147 static int spear_adc_read_raw(struct iio_dev *indio_dev, 148 struct iio_chan_spec const *chan, 149 int *val, 150 int *val2, 151 long mask) 152 { 153 struct spear_adc_state *st = iio_priv(indio_dev); 154 u32 status; 155 156 switch (mask) { 157 case IIO_CHAN_INFO_RAW: 158 mutex_lock(&st->lock); 159 160 status = SPEAR_ADC_STATUS_CHANNEL_NUM(chan->channel) | 161 SPEAR_ADC_STATUS_AVG_SAMPLE(st->avg_samples) | 162 SPEAR_ADC_STATUS_START_CONVERSION | 163 SPEAR_ADC_STATUS_ADC_ENABLE; 164 if (st->vref_external == 0) 165 status |= SPEAR_ADC_STATUS_VREF_INTERNAL; 166 167 spear_adc_set_status(st, status); 168 wait_for_completion(&st->completion); /* set by ISR */ 169 *val = st->value; 170 171 mutex_unlock(&st->lock); 172 173 return IIO_VAL_INT; 174 175 case IIO_CHAN_INFO_SCALE: 176 *val = st->vref_external; 177 *val2 = SPEAR_ADC_DATA_BITS; 178 return IIO_VAL_FRACTIONAL_LOG2; 179 case IIO_CHAN_INFO_SAMP_FREQ: 180 *val = st->current_clk; 181 return IIO_VAL_INT; 182 } 183 184 return -EINVAL; 185 } 186 187 static int spear_adc_write_raw(struct iio_dev *indio_dev, 188 struct iio_chan_spec const *chan, 189 int val, 190 int val2, 191 long mask) 192 { 193 struct spear_adc_state *st = iio_priv(indio_dev); 194 int ret = 0; 195 196 if (mask != IIO_CHAN_INFO_SAMP_FREQ) 197 return -EINVAL; 198 199 mutex_lock(&st->lock); 200 201 if ((val < SPEAR_ADC_CLK_MIN) || 202 (val > SPEAR_ADC_CLK_MAX) || 203 (val2 != 0)) { 204 ret = -EINVAL; 205 goto out; 206 } 207 208 spear_adc_set_clk(st, val); 209 210 out: 211 mutex_unlock(&st->lock); 212 return ret; 213 } 214 215 #define SPEAR_ADC_CHAN(idx) { \ 216 .type = IIO_VOLTAGE, \ 217 .indexed = 1, \ 218 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \ 219 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \ 220 .info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ),\ 221 .channel = idx, \ 222 } 223 224 static const struct iio_chan_spec spear_adc_iio_channels[] = { 225 SPEAR_ADC_CHAN(0), 226 SPEAR_ADC_CHAN(1), 227 SPEAR_ADC_CHAN(2), 228 SPEAR_ADC_CHAN(3), 229 SPEAR_ADC_CHAN(4), 230 SPEAR_ADC_CHAN(5), 231 SPEAR_ADC_CHAN(6), 232 SPEAR_ADC_CHAN(7), 233 }; 234 235 static irqreturn_t spear_adc_isr(int irq, void *dev_id) 236 { 237 struct spear_adc_state *st = dev_id; 238 239 /* Read value to clear IRQ */ 240 st->value = spear_adc_get_average(st); 241 complete(&st->completion); 242 243 return IRQ_HANDLED; 244 } 245 246 static int spear_adc_configure(struct spear_adc_state *st) 247 { 248 int i; 249 250 /* Reset ADC core */ 251 spear_adc_set_status(st, 0); 252 __raw_writel(0, &st->adc_base_spear6xx->clk); 253 for (i = 0; i < 8; i++) 254 spear_adc_set_ctrl(st, i, 0); 255 spear_adc_set_scanrate(st, 0); 256 257 spear_adc_set_clk(st, st->sampling_freq); 258 259 return 0; 260 } 261 262 static const struct iio_info spear_adc_info = { 263 .read_raw = &spear_adc_read_raw, 264 .write_raw = &spear_adc_write_raw, 265 }; 266 267 static int spear_adc_probe(struct platform_device *pdev) 268 { 269 struct device_node *np = pdev->dev.of_node; 270 struct device *dev = &pdev->dev; 271 struct spear_adc_state *st; 272 struct iio_dev *indio_dev = NULL; 273 int ret = -ENODEV; 274 int irq; 275 276 indio_dev = devm_iio_device_alloc(dev, sizeof(struct spear_adc_state)); 277 if (!indio_dev) { 278 dev_err(dev, "failed allocating iio device\n"); 279 return -ENOMEM; 280 } 281 282 st = iio_priv(indio_dev); 283 284 mutex_init(&st->lock); 285 286 st->np = np; 287 288 /* 289 * SPEAr600 has a different register layout than other SPEAr SoC's 290 * (e.g. SPEAr3xx). Let's provide two register base addresses 291 * to support multi-arch kernels. 292 */ 293 st->adc_base_spear6xx = devm_platform_ioremap_resource(pdev, 0); 294 if (IS_ERR(st->adc_base_spear6xx)) 295 return PTR_ERR(st->adc_base_spear6xx); 296 297 st->adc_base_spear3xx = 298 (struct adc_regs_spear3xx __iomem *)st->adc_base_spear6xx; 299 300 st->clk = devm_clk_get(dev, NULL); 301 if (IS_ERR(st->clk)) { 302 dev_err(dev, "failed getting clock\n"); 303 return PTR_ERR(st->clk); 304 } 305 306 ret = clk_prepare_enable(st->clk); 307 if (ret) { 308 dev_err(dev, "failed enabling clock\n"); 309 return ret; 310 } 311 312 irq = platform_get_irq(pdev, 0); 313 if (irq <= 0) { 314 ret = -EINVAL; 315 goto errout2; 316 } 317 318 ret = devm_request_irq(dev, irq, spear_adc_isr, 0, SPEAR_ADC_MOD_NAME, 319 st); 320 if (ret < 0) { 321 dev_err(dev, "failed requesting interrupt\n"); 322 goto errout2; 323 } 324 325 if (of_property_read_u32(np, "sampling-frequency", 326 &st->sampling_freq)) { 327 dev_err(dev, "sampling-frequency missing in DT\n"); 328 ret = -EINVAL; 329 goto errout2; 330 } 331 332 /* 333 * Optional avg_samples defaults to 0, resulting in single data 334 * conversion 335 */ 336 of_property_read_u32(np, "average-samples", &st->avg_samples); 337 338 /* 339 * Optional vref_external defaults to 0, resulting in internal vref 340 * selection 341 */ 342 of_property_read_u32(np, "vref-external", &st->vref_external); 343 344 spear_adc_configure(st); 345 346 platform_set_drvdata(pdev, indio_dev); 347 348 init_completion(&st->completion); 349 350 indio_dev->name = SPEAR_ADC_MOD_NAME; 351 indio_dev->info = &spear_adc_info; 352 indio_dev->modes = INDIO_DIRECT_MODE; 353 indio_dev->channels = spear_adc_iio_channels; 354 indio_dev->num_channels = ARRAY_SIZE(spear_adc_iio_channels); 355 356 ret = iio_device_register(indio_dev); 357 if (ret) 358 goto errout2; 359 360 dev_info(dev, "SPEAR ADC driver loaded, IRQ %d\n", irq); 361 362 return 0; 363 364 errout2: 365 clk_disable_unprepare(st->clk); 366 return ret; 367 } 368 369 static int spear_adc_remove(struct platform_device *pdev) 370 { 371 struct iio_dev *indio_dev = platform_get_drvdata(pdev); 372 struct spear_adc_state *st = iio_priv(indio_dev); 373 374 iio_device_unregister(indio_dev); 375 clk_disable_unprepare(st->clk); 376 377 return 0; 378 } 379 380 #ifdef CONFIG_OF 381 static const struct of_device_id spear_adc_dt_ids[] = { 382 { .compatible = "st,spear600-adc", }, 383 { /* sentinel */ } 384 }; 385 MODULE_DEVICE_TABLE(of, spear_adc_dt_ids); 386 #endif 387 388 static struct platform_driver spear_adc_driver = { 389 .probe = spear_adc_probe, 390 .remove = spear_adc_remove, 391 .driver = { 392 .name = SPEAR_ADC_MOD_NAME, 393 .of_match_table = of_match_ptr(spear_adc_dt_ids), 394 }, 395 }; 396 397 module_platform_driver(spear_adc_driver); 398 399 MODULE_AUTHOR("Stefan Roese <sr@denx.de>"); 400 MODULE_DESCRIPTION("SPEAr ADC driver"); 401 MODULE_LICENSE("GPL"); 402