1 // SPDX-License-Identifier: GPL-2.0 2 // 3 // spi-mt7621.c -- MediaTek MT7621 SPI controller driver 4 // 5 // Copyright (C) 2011 Sergiy <piratfm@gmail.com> 6 // Copyright (C) 2011-2013 Gabor Juhos <juhosg@openwrt.org> 7 // Copyright (C) 2014-2015 Felix Fietkau <nbd@nbd.name> 8 // 9 // Some parts are based on spi-orion.c: 10 // Author: Shadi Ammouri <shadi@marvell.com> 11 // Copyright (C) 2007-2008 Marvell Ltd. 12 13 #include <linux/clk.h> 14 #include <linux/delay.h> 15 #include <linux/io.h> 16 #include <linux/module.h> 17 #include <linux/of.h> 18 #include <linux/of_device.h> 19 #include <linux/platform_device.h> 20 #include <linux/reset.h> 21 #include <linux/spi/spi.h> 22 23 #define DRIVER_NAME "spi-mt7621" 24 25 /* in usec */ 26 #define RALINK_SPI_WAIT_MAX_LOOP 2000 27 28 /* SPISTAT register bit field */ 29 #define SPISTAT_BUSY BIT(0) 30 31 #define MT7621_SPI_TRANS 0x00 32 #define SPITRANS_BUSY BIT(16) 33 34 #define MT7621_SPI_OPCODE 0x04 35 #define MT7621_SPI_DATA0 0x08 36 #define MT7621_SPI_DATA4 0x18 37 #define SPI_CTL_TX_RX_CNT_MASK 0xff 38 #define SPI_CTL_START BIT(8) 39 40 #define MT7621_SPI_MASTER 0x28 41 #define MASTER_MORE_BUFMODE BIT(2) 42 #define MASTER_FULL_DUPLEX BIT(10) 43 #define MASTER_RS_CLK_SEL GENMASK(27, 16) 44 #define MASTER_RS_CLK_SEL_SHIFT 16 45 #define MASTER_RS_SLAVE_SEL GENMASK(31, 29) 46 47 #define MT7621_SPI_MOREBUF 0x2c 48 #define MT7621_SPI_POLAR 0x38 49 #define MT7621_SPI_SPACE 0x3c 50 51 #define MT7621_CPHA BIT(5) 52 #define MT7621_CPOL BIT(4) 53 #define MT7621_LSB_FIRST BIT(3) 54 55 struct mt7621_spi { 56 struct spi_controller *host; 57 void __iomem *base; 58 unsigned int sys_freq; 59 unsigned int speed; 60 int pending_write; 61 }; 62 63 static inline struct mt7621_spi *spidev_to_mt7621_spi(struct spi_device *spi) 64 { 65 return spi_controller_get_devdata(spi->controller); 66 } 67 68 static inline u32 mt7621_spi_read(struct mt7621_spi *rs, u32 reg) 69 { 70 return ioread32(rs->base + reg); 71 } 72 73 static inline void mt7621_spi_write(struct mt7621_spi *rs, u32 reg, u32 val) 74 { 75 iowrite32(val, rs->base + reg); 76 } 77 78 static void mt7621_spi_set_cs(struct spi_device *spi, int enable) 79 { 80 struct mt7621_spi *rs = spidev_to_mt7621_spi(spi); 81 int cs = spi_get_chipselect(spi, 0); 82 u32 polar = 0; 83 u32 host; 84 85 /* 86 * Select SPI device 7, enable "more buffer mode" and disable 87 * full-duplex (only half-duplex really works on this chip 88 * reliably) 89 */ 90 host = mt7621_spi_read(rs, MT7621_SPI_MASTER); 91 host |= MASTER_RS_SLAVE_SEL | MASTER_MORE_BUFMODE; 92 host &= ~MASTER_FULL_DUPLEX; 93 mt7621_spi_write(rs, MT7621_SPI_MASTER, host); 94 95 rs->pending_write = 0; 96 97 if (enable) 98 polar = BIT(cs); 99 mt7621_spi_write(rs, MT7621_SPI_POLAR, polar); 100 } 101 102 static int mt7621_spi_prepare(struct spi_device *spi, unsigned int speed) 103 { 104 struct mt7621_spi *rs = spidev_to_mt7621_spi(spi); 105 u32 rate; 106 u32 reg; 107 108 dev_dbg(&spi->dev, "speed:%u\n", speed); 109 110 rate = DIV_ROUND_UP(rs->sys_freq, speed); 111 dev_dbg(&spi->dev, "rate-1:%u\n", rate); 112 113 if (rate > 4097) 114 return -EINVAL; 115 116 if (rate < 2) 117 rate = 2; 118 119 reg = mt7621_spi_read(rs, MT7621_SPI_MASTER); 120 reg &= ~MASTER_RS_CLK_SEL; 121 reg |= (rate - 2) << MASTER_RS_CLK_SEL_SHIFT; 122 rs->speed = speed; 123 124 reg &= ~MT7621_LSB_FIRST; 125 if (spi->mode & SPI_LSB_FIRST) 126 reg |= MT7621_LSB_FIRST; 127 128 /* 129 * This SPI controller seems to be tested on SPI flash only and some 130 * bits are swizzled under other SPI modes probably due to incorrect 131 * wiring inside the silicon. Only mode 0 works correctly. 132 */ 133 reg &= ~(MT7621_CPHA | MT7621_CPOL); 134 135 mt7621_spi_write(rs, MT7621_SPI_MASTER, reg); 136 137 return 0; 138 } 139 140 static inline int mt7621_spi_wait_till_ready(struct mt7621_spi *rs) 141 { 142 int i; 143 144 for (i = 0; i < RALINK_SPI_WAIT_MAX_LOOP; i++) { 145 u32 status; 146 147 status = mt7621_spi_read(rs, MT7621_SPI_TRANS); 148 if ((status & SPITRANS_BUSY) == 0) 149 return 0; 150 cpu_relax(); 151 udelay(1); 152 } 153 154 return -ETIMEDOUT; 155 } 156 157 static void mt7621_spi_read_half_duplex(struct mt7621_spi *rs, 158 int rx_len, u8 *buf) 159 { 160 int tx_len; 161 162 /* 163 * Combine with any pending write, and perform one or more half-duplex 164 * transactions reading 'len' bytes. Data to be written is already in 165 * MT7621_SPI_DATA. 166 */ 167 tx_len = rs->pending_write; 168 rs->pending_write = 0; 169 170 while (rx_len || tx_len) { 171 int i; 172 u32 val = (min(tx_len, 4) * 8) << 24; 173 int rx = min(rx_len, 32); 174 175 if (tx_len > 4) 176 val |= (tx_len - 4) * 8; 177 val |= (rx * 8) << 12; 178 mt7621_spi_write(rs, MT7621_SPI_MOREBUF, val); 179 180 tx_len = 0; 181 182 val = mt7621_spi_read(rs, MT7621_SPI_TRANS); 183 val |= SPI_CTL_START; 184 mt7621_spi_write(rs, MT7621_SPI_TRANS, val); 185 186 mt7621_spi_wait_till_ready(rs); 187 188 for (i = 0; i < rx; i++) { 189 if ((i % 4) == 0) 190 val = mt7621_spi_read(rs, MT7621_SPI_DATA0 + i); 191 *buf++ = val & 0xff; 192 val >>= 8; 193 } 194 195 rx_len -= i; 196 } 197 } 198 199 static inline void mt7621_spi_flush(struct mt7621_spi *rs) 200 { 201 mt7621_spi_read_half_duplex(rs, 0, NULL); 202 } 203 204 static void mt7621_spi_write_half_duplex(struct mt7621_spi *rs, 205 int tx_len, const u8 *buf) 206 { 207 int len = rs->pending_write; 208 int val = 0; 209 210 if (len & 3) { 211 val = mt7621_spi_read(rs, MT7621_SPI_OPCODE + (len & ~3)); 212 if (len < 4) { 213 val <<= (4 - len) * 8; 214 val = swab32(val); 215 } 216 } 217 218 while (tx_len > 0) { 219 if (len >= 36) { 220 rs->pending_write = len; 221 mt7621_spi_flush(rs); 222 len = 0; 223 } 224 225 val |= *buf++ << (8 * (len & 3)); 226 len++; 227 if ((len & 3) == 0) { 228 if (len == 4) 229 /* The byte-order of the opcode is weird! */ 230 val = swab32(val); 231 mt7621_spi_write(rs, MT7621_SPI_OPCODE + len - 4, val); 232 val = 0; 233 } 234 tx_len -= 1; 235 } 236 237 if (len & 3) { 238 if (len < 4) { 239 val = swab32(val); 240 val >>= (4 - len) * 8; 241 } 242 mt7621_spi_write(rs, MT7621_SPI_OPCODE + (len & ~3), val); 243 } 244 245 rs->pending_write = len; 246 } 247 248 static int mt7621_spi_transfer_one_message(struct spi_controller *host, 249 struct spi_message *m) 250 { 251 struct mt7621_spi *rs = spi_controller_get_devdata(host); 252 struct spi_device *spi = m->spi; 253 unsigned int speed = spi->max_speed_hz; 254 struct spi_transfer *t = NULL; 255 int status = 0; 256 257 mt7621_spi_wait_till_ready(rs); 258 259 list_for_each_entry(t, &m->transfers, transfer_list) 260 if (t->speed_hz < speed) 261 speed = t->speed_hz; 262 263 if (mt7621_spi_prepare(spi, speed)) { 264 status = -EIO; 265 goto msg_done; 266 } 267 268 /* Assert CS */ 269 mt7621_spi_set_cs(spi, 1); 270 271 m->actual_length = 0; 272 list_for_each_entry(t, &m->transfers, transfer_list) { 273 if ((t->rx_buf) && (t->tx_buf)) { 274 /* 275 * This controller will shift some extra data out 276 * of spi_opcode if (mosi_bit_cnt > 0) && 277 * (cmd_bit_cnt == 0). So the claimed full-duplex 278 * support is broken since we have no way to read 279 * the MISO value during that bit. 280 */ 281 status = -EIO; 282 goto msg_done; 283 } else if (t->rx_buf) { 284 mt7621_spi_read_half_duplex(rs, t->len, t->rx_buf); 285 } else if (t->tx_buf) { 286 mt7621_spi_write_half_duplex(rs, t->len, t->tx_buf); 287 } 288 m->actual_length += t->len; 289 } 290 291 /* Flush data and deassert CS */ 292 mt7621_spi_flush(rs); 293 mt7621_spi_set_cs(spi, 0); 294 295 msg_done: 296 m->status = status; 297 spi_finalize_current_message(host); 298 299 return 0; 300 } 301 302 static int mt7621_spi_setup(struct spi_device *spi) 303 { 304 struct mt7621_spi *rs = spidev_to_mt7621_spi(spi); 305 306 if ((spi->max_speed_hz == 0) || 307 (spi->max_speed_hz > (rs->sys_freq / 2))) 308 spi->max_speed_hz = rs->sys_freq / 2; 309 310 if (spi->max_speed_hz < (rs->sys_freq / 4097)) { 311 dev_err(&spi->dev, "setup: requested speed is too low %d Hz\n", 312 spi->max_speed_hz); 313 return -EINVAL; 314 } 315 316 return 0; 317 } 318 319 static const struct of_device_id mt7621_spi_match[] = { 320 { .compatible = "ralink,mt7621-spi" }, 321 {}, 322 }; 323 MODULE_DEVICE_TABLE(of, mt7621_spi_match); 324 325 static int mt7621_spi_probe(struct platform_device *pdev) 326 { 327 const struct of_device_id *match; 328 struct spi_controller *host; 329 struct mt7621_spi *rs; 330 void __iomem *base; 331 struct clk *clk; 332 int ret; 333 334 match = of_match_device(mt7621_spi_match, &pdev->dev); 335 if (!match) 336 return -EINVAL; 337 338 base = devm_platform_ioremap_resource(pdev, 0); 339 if (IS_ERR(base)) 340 return PTR_ERR(base); 341 342 clk = devm_clk_get_enabled(&pdev->dev, NULL); 343 if (IS_ERR(clk)) 344 return dev_err_probe(&pdev->dev, PTR_ERR(clk), 345 "unable to get SYS clock\n"); 346 347 host = devm_spi_alloc_host(&pdev->dev, sizeof(*rs)); 348 if (!host) { 349 dev_info(&pdev->dev, "host allocation failed\n"); 350 return -ENOMEM; 351 } 352 353 host->mode_bits = SPI_LSB_FIRST; 354 host->flags = SPI_CONTROLLER_HALF_DUPLEX; 355 host->setup = mt7621_spi_setup; 356 host->transfer_one_message = mt7621_spi_transfer_one_message; 357 host->bits_per_word_mask = SPI_BPW_MASK(8); 358 host->dev.of_node = pdev->dev.of_node; 359 host->num_chipselect = 2; 360 361 dev_set_drvdata(&pdev->dev, host); 362 363 rs = spi_controller_get_devdata(host); 364 rs->base = base; 365 rs->host = host; 366 rs->sys_freq = clk_get_rate(clk); 367 rs->pending_write = 0; 368 dev_info(&pdev->dev, "sys_freq: %u\n", rs->sys_freq); 369 370 ret = device_reset(&pdev->dev); 371 if (ret) { 372 dev_err(&pdev->dev, "SPI reset failed!\n"); 373 return ret; 374 } 375 376 return devm_spi_register_controller(&pdev->dev, host); 377 } 378 379 MODULE_ALIAS("platform:" DRIVER_NAME); 380 381 static struct platform_driver mt7621_spi_driver = { 382 .driver = { 383 .name = DRIVER_NAME, 384 .of_match_table = mt7621_spi_match, 385 }, 386 .probe = mt7621_spi_probe, 387 }; 388 389 module_platform_driver(mt7621_spi_driver); 390 391 MODULE_DESCRIPTION("MT7621 SPI driver"); 392 MODULE_AUTHOR("Felix Fietkau <nbd@nbd.name>"); 393 MODULE_LICENSE("GPL"); 394