1 /* 2 * Freescale i.MX28 SPI driver 3 * 4 * Copyright (C) 2011 Marek Vasut <marek.vasut@gmail.com> 5 * on behalf of DENX Software Engineering GmbH 6 * 7 * SPDX-License-Identifier: GPL-2.0+ 8 * 9 * NOTE: This driver only supports the SPI-controller chipselects, 10 * GPIO driven chipselects are not supported. 11 */ 12 13 #include <common.h> 14 #include <malloc.h> 15 #include <memalign.h> 16 #include <spi.h> 17 #include <linux/errno.h> 18 #include <asm/io.h> 19 #include <asm/arch/clock.h> 20 #include <asm/arch/imx-regs.h> 21 #include <asm/arch/sys_proto.h> 22 #include <asm/mach-imx/dma.h> 23 24 #define MXS_SPI_MAX_TIMEOUT 1000000 25 #define MXS_SPI_PORT_OFFSET 0x2000 26 #define MXS_SSP_CHIPSELECT_MASK 0x00300000 27 #define MXS_SSP_CHIPSELECT_SHIFT 20 28 29 #define MXSSSP_SMALL_TRANSFER 512 30 31 struct mxs_spi_slave { 32 struct spi_slave slave; 33 uint32_t max_khz; 34 uint32_t mode; 35 struct mxs_ssp_regs *regs; 36 }; 37 38 static inline struct mxs_spi_slave *to_mxs_slave(struct spi_slave *slave) 39 { 40 return container_of(slave, struct mxs_spi_slave, slave); 41 } 42 43 void spi_init(void) 44 { 45 } 46 47 int spi_cs_is_valid(unsigned int bus, unsigned int cs) 48 { 49 /* MXS SPI: 4 ports and 3 chip selects maximum */ 50 if (!mxs_ssp_bus_id_valid(bus) || cs > 2) 51 return 0; 52 else 53 return 1; 54 } 55 56 struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs, 57 unsigned int max_hz, unsigned int mode) 58 { 59 struct mxs_spi_slave *mxs_slave; 60 61 if (!spi_cs_is_valid(bus, cs)) { 62 printf("mxs_spi: invalid bus %d / chip select %d\n", bus, cs); 63 return NULL; 64 } 65 66 mxs_slave = spi_alloc_slave(struct mxs_spi_slave, bus, cs); 67 if (!mxs_slave) 68 return NULL; 69 70 if (mxs_dma_init_channel(MXS_DMA_CHANNEL_AHB_APBH_SSP0 + bus)) 71 goto err_init; 72 73 mxs_slave->max_khz = max_hz / 1000; 74 mxs_slave->mode = mode; 75 mxs_slave->regs = mxs_ssp_regs_by_bus(bus); 76 77 return &mxs_slave->slave; 78 79 err_init: 80 free(mxs_slave); 81 return NULL; 82 } 83 84 void spi_free_slave(struct spi_slave *slave) 85 { 86 struct mxs_spi_slave *mxs_slave = to_mxs_slave(slave); 87 free(mxs_slave); 88 } 89 90 int spi_claim_bus(struct spi_slave *slave) 91 { 92 struct mxs_spi_slave *mxs_slave = to_mxs_slave(slave); 93 struct mxs_ssp_regs *ssp_regs = mxs_slave->regs; 94 uint32_t reg = 0; 95 96 mxs_reset_block(&ssp_regs->hw_ssp_ctrl0_reg); 97 98 writel((slave->cs << MXS_SSP_CHIPSELECT_SHIFT) | 99 SSP_CTRL0_BUS_WIDTH_ONE_BIT, 100 &ssp_regs->hw_ssp_ctrl0); 101 102 reg = SSP_CTRL1_SSP_MODE_SPI | SSP_CTRL1_WORD_LENGTH_EIGHT_BITS; 103 reg |= (mxs_slave->mode & SPI_CPOL) ? SSP_CTRL1_POLARITY : 0; 104 reg |= (mxs_slave->mode & SPI_CPHA) ? SSP_CTRL1_PHASE : 0; 105 writel(reg, &ssp_regs->hw_ssp_ctrl1); 106 107 writel(0, &ssp_regs->hw_ssp_cmd0); 108 109 mxs_set_ssp_busclock(slave->bus, mxs_slave->max_khz); 110 111 return 0; 112 } 113 114 void spi_release_bus(struct spi_slave *slave) 115 { 116 } 117 118 static void mxs_spi_start_xfer(struct mxs_ssp_regs *ssp_regs) 119 { 120 writel(SSP_CTRL0_LOCK_CS, &ssp_regs->hw_ssp_ctrl0_set); 121 writel(SSP_CTRL0_IGNORE_CRC, &ssp_regs->hw_ssp_ctrl0_clr); 122 } 123 124 static void mxs_spi_end_xfer(struct mxs_ssp_regs *ssp_regs) 125 { 126 writel(SSP_CTRL0_LOCK_CS, &ssp_regs->hw_ssp_ctrl0_clr); 127 writel(SSP_CTRL0_IGNORE_CRC, &ssp_regs->hw_ssp_ctrl0_set); 128 } 129 130 static int mxs_spi_xfer_pio(struct mxs_spi_slave *slave, 131 char *data, int length, int write, unsigned long flags) 132 { 133 struct mxs_ssp_regs *ssp_regs = slave->regs; 134 135 if (flags & SPI_XFER_BEGIN) 136 mxs_spi_start_xfer(ssp_regs); 137 138 while (length--) { 139 /* We transfer 1 byte */ 140 #if defined(CONFIG_MX23) 141 writel(SSP_CTRL0_XFER_COUNT_MASK, &ssp_regs->hw_ssp_ctrl0_clr); 142 writel(1, &ssp_regs->hw_ssp_ctrl0_set); 143 #elif defined(CONFIG_MX28) 144 writel(1, &ssp_regs->hw_ssp_xfer_size); 145 #endif 146 147 if ((flags & SPI_XFER_END) && !length) 148 mxs_spi_end_xfer(ssp_regs); 149 150 if (write) 151 writel(SSP_CTRL0_READ, &ssp_regs->hw_ssp_ctrl0_clr); 152 else 153 writel(SSP_CTRL0_READ, &ssp_regs->hw_ssp_ctrl0_set); 154 155 writel(SSP_CTRL0_RUN, &ssp_regs->hw_ssp_ctrl0_set); 156 157 if (mxs_wait_mask_set(&ssp_regs->hw_ssp_ctrl0_reg, 158 SSP_CTRL0_RUN, MXS_SPI_MAX_TIMEOUT)) { 159 printf("MXS SPI: Timeout waiting for start\n"); 160 return -ETIMEDOUT; 161 } 162 163 if (write) 164 writel(*data++, &ssp_regs->hw_ssp_data); 165 166 writel(SSP_CTRL0_DATA_XFER, &ssp_regs->hw_ssp_ctrl0_set); 167 168 if (!write) { 169 if (mxs_wait_mask_clr(&ssp_regs->hw_ssp_status_reg, 170 SSP_STATUS_FIFO_EMPTY, MXS_SPI_MAX_TIMEOUT)) { 171 printf("MXS SPI: Timeout waiting for data\n"); 172 return -ETIMEDOUT; 173 } 174 175 *data = readl(&ssp_regs->hw_ssp_data); 176 data++; 177 } 178 179 if (mxs_wait_mask_clr(&ssp_regs->hw_ssp_ctrl0_reg, 180 SSP_CTRL0_RUN, MXS_SPI_MAX_TIMEOUT)) { 181 printf("MXS SPI: Timeout waiting for finish\n"); 182 return -ETIMEDOUT; 183 } 184 } 185 186 return 0; 187 } 188 189 static int mxs_spi_xfer_dma(struct mxs_spi_slave *slave, 190 char *data, int length, int write, unsigned long flags) 191 { 192 const int xfer_max_sz = 0xff00; 193 const int desc_count = DIV_ROUND_UP(length, xfer_max_sz) + 1; 194 struct mxs_ssp_regs *ssp_regs = slave->regs; 195 struct mxs_dma_desc *dp; 196 uint32_t ctrl0; 197 uint32_t cache_data_count; 198 const uint32_t dstart = (uint32_t)data; 199 int dmach; 200 int tl; 201 int ret = 0; 202 203 #if defined(CONFIG_MX23) 204 const int mxs_spi_pio_words = 1; 205 #elif defined(CONFIG_MX28) 206 const int mxs_spi_pio_words = 4; 207 #endif 208 209 ALLOC_CACHE_ALIGN_BUFFER(struct mxs_dma_desc, desc, desc_count); 210 211 memset(desc, 0, sizeof(struct mxs_dma_desc) * desc_count); 212 213 ctrl0 = readl(&ssp_regs->hw_ssp_ctrl0); 214 ctrl0 |= SSP_CTRL0_DATA_XFER; 215 216 if (flags & SPI_XFER_BEGIN) 217 ctrl0 |= SSP_CTRL0_LOCK_CS; 218 if (!write) 219 ctrl0 |= SSP_CTRL0_READ; 220 221 if (length % ARCH_DMA_MINALIGN) 222 cache_data_count = roundup(length, ARCH_DMA_MINALIGN); 223 else 224 cache_data_count = length; 225 226 /* Flush data to DRAM so DMA can pick them up */ 227 if (write) 228 flush_dcache_range(dstart, dstart + cache_data_count); 229 230 /* Invalidate the area, so no writeback into the RAM races with DMA */ 231 invalidate_dcache_range(dstart, dstart + cache_data_count); 232 233 dmach = MXS_DMA_CHANNEL_AHB_APBH_SSP0 + slave->slave.bus; 234 235 dp = desc; 236 while (length) { 237 dp->address = (dma_addr_t)dp; 238 dp->cmd.address = (dma_addr_t)data; 239 240 /* 241 * This is correct, even though it does indeed look insane. 242 * I hereby have to, wholeheartedly, thank Freescale Inc., 243 * for always inventing insane hardware and keeping me busy 244 * and employed ;-) 245 */ 246 if (write) 247 dp->cmd.data = MXS_DMA_DESC_COMMAND_DMA_READ; 248 else 249 dp->cmd.data = MXS_DMA_DESC_COMMAND_DMA_WRITE; 250 251 /* 252 * The DMA controller can transfer large chunks (64kB) at 253 * time by setting the transfer length to 0. Setting tl to 254 * 0x10000 will overflow below and make .data contain 0. 255 * Otherwise, 0xff00 is the transfer maximum. 256 */ 257 if (length >= 0x10000) 258 tl = 0x10000; 259 else 260 tl = min(length, xfer_max_sz); 261 262 dp->cmd.data |= 263 ((tl & 0xffff) << MXS_DMA_DESC_BYTES_OFFSET) | 264 (mxs_spi_pio_words << MXS_DMA_DESC_PIO_WORDS_OFFSET) | 265 MXS_DMA_DESC_HALT_ON_TERMINATE | 266 MXS_DMA_DESC_TERMINATE_FLUSH; 267 268 data += tl; 269 length -= tl; 270 271 if (!length) { 272 dp->cmd.data |= MXS_DMA_DESC_IRQ | MXS_DMA_DESC_DEC_SEM; 273 274 if (flags & SPI_XFER_END) { 275 ctrl0 &= ~SSP_CTRL0_LOCK_CS; 276 ctrl0 |= SSP_CTRL0_IGNORE_CRC; 277 } 278 } 279 280 /* 281 * Write CTRL0, CMD0, CMD1 and XFER_SIZE registers in 282 * case of MX28, write only CTRL0 in case of MX23 due 283 * to the difference in register layout. It is utterly 284 * essential that the XFER_SIZE register is written on 285 * a per-descriptor basis with the same size as is the 286 * descriptor! 287 */ 288 dp->cmd.pio_words[0] = ctrl0; 289 #ifdef CONFIG_MX28 290 dp->cmd.pio_words[1] = 0; 291 dp->cmd.pio_words[2] = 0; 292 dp->cmd.pio_words[3] = tl; 293 #endif 294 295 mxs_dma_desc_append(dmach, dp); 296 297 dp++; 298 } 299 300 if (mxs_dma_go(dmach)) 301 ret = -EINVAL; 302 303 /* The data arrived into DRAM, invalidate cache over them */ 304 if (!write) 305 invalidate_dcache_range(dstart, dstart + cache_data_count); 306 307 return ret; 308 } 309 310 int spi_xfer(struct spi_slave *slave, unsigned int bitlen, 311 const void *dout, void *din, unsigned long flags) 312 { 313 struct mxs_spi_slave *mxs_slave = to_mxs_slave(slave); 314 struct mxs_ssp_regs *ssp_regs = mxs_slave->regs; 315 int len = bitlen / 8; 316 char dummy; 317 int write = 0; 318 char *data = NULL; 319 int dma = 1; 320 321 if (bitlen == 0) { 322 if (flags & SPI_XFER_END) { 323 din = (void *)&dummy; 324 len = 1; 325 } else 326 return 0; 327 } 328 329 /* Half-duplex only */ 330 if (din && dout) 331 return -EINVAL; 332 /* No data */ 333 if (!din && !dout) 334 return 0; 335 336 if (dout) { 337 data = (char *)dout; 338 write = 1; 339 } else if (din) { 340 data = (char *)din; 341 write = 0; 342 } 343 344 /* 345 * Check for alignment, if the buffer is aligned, do DMA transfer, 346 * PIO otherwise. This is a temporary workaround until proper bounce 347 * buffer is in place. 348 */ 349 if (dma) { 350 if (((uint32_t)data) & (ARCH_DMA_MINALIGN - 1)) 351 dma = 0; 352 if (((uint32_t)len) & (ARCH_DMA_MINALIGN - 1)) 353 dma = 0; 354 } 355 356 if (!dma || (len < MXSSSP_SMALL_TRANSFER)) { 357 writel(SSP_CTRL1_DMA_ENABLE, &ssp_regs->hw_ssp_ctrl1_clr); 358 return mxs_spi_xfer_pio(mxs_slave, data, len, write, flags); 359 } else { 360 writel(SSP_CTRL1_DMA_ENABLE, &ssp_regs->hw_ssp_ctrl1_set); 361 return mxs_spi_xfer_dma(mxs_slave, data, len, write, flags); 362 } 363 } 364