1 /* 2 * Copyright (C) 2012 - 2014 Allwinner Tech 3 * Pan Nan <pannan@allwinnertech.com> 4 * 5 * Copyright (C) 2014 Maxime Ripard 6 * Maxime Ripard <maxime.ripard@free-electrons.com> 7 * 8 * This program is free software; you can redistribute it and/or 9 * modify it under the terms of the GNU General Public License as 10 * published by the Free Software Foundation; either version 2 of 11 * the License, or (at your option) any later version. 12 */ 13 14 #include <linux/clk.h> 15 #include <linux/delay.h> 16 #include <linux/device.h> 17 #include <linux/interrupt.h> 18 #include <linux/io.h> 19 #include <linux/module.h> 20 #include <linux/platform_device.h> 21 #include <linux/pm_runtime.h> 22 23 #include <linux/spi/spi.h> 24 25 #define SUN4I_FIFO_DEPTH 64 26 27 #define SUN4I_RXDATA_REG 0x00 28 29 #define SUN4I_TXDATA_REG 0x04 30 31 #define SUN4I_CTL_REG 0x08 32 #define SUN4I_CTL_ENABLE BIT(0) 33 #define SUN4I_CTL_MASTER BIT(1) 34 #define SUN4I_CTL_CPHA BIT(2) 35 #define SUN4I_CTL_CPOL BIT(3) 36 #define SUN4I_CTL_CS_ACTIVE_LOW BIT(4) 37 #define SUN4I_CTL_LMTF BIT(6) 38 #define SUN4I_CTL_TF_RST BIT(8) 39 #define SUN4I_CTL_RF_RST BIT(9) 40 #define SUN4I_CTL_XCH BIT(10) 41 #define SUN4I_CTL_CS_MASK 0x3000 42 #define SUN4I_CTL_CS(cs) (((cs) << 12) & SUN4I_CTL_CS_MASK) 43 #define SUN4I_CTL_DHB BIT(15) 44 #define SUN4I_CTL_CS_MANUAL BIT(16) 45 #define SUN4I_CTL_CS_LEVEL BIT(17) 46 #define SUN4I_CTL_TP BIT(18) 47 48 #define SUN4I_INT_CTL_REG 0x0c 49 #define SUN4I_INT_CTL_TC BIT(16) 50 51 #define SUN4I_INT_STA_REG 0x10 52 53 #define SUN4I_DMA_CTL_REG 0x14 54 55 #define SUN4I_WAIT_REG 0x18 56 57 #define SUN4I_CLK_CTL_REG 0x1c 58 #define SUN4I_CLK_CTL_CDR2_MASK 0xff 59 #define SUN4I_CLK_CTL_CDR2(div) ((div) & SUN4I_CLK_CTL_CDR2_MASK) 60 #define SUN4I_CLK_CTL_CDR1_MASK 0xf 61 #define SUN4I_CLK_CTL_CDR1(div) (((div) & SUN4I_CLK_CTL_CDR1_MASK) << 8) 62 #define SUN4I_CLK_CTL_DRS BIT(12) 63 64 #define SUN4I_BURST_CNT_REG 0x20 65 #define SUN4I_BURST_CNT(cnt) ((cnt) & 0xffffff) 66 67 #define SUN4I_XMIT_CNT_REG 0x24 68 #define SUN4I_XMIT_CNT(cnt) ((cnt) & 0xffffff) 69 70 #define SUN4I_FIFO_STA_REG 0x28 71 #define SUN4I_FIFO_STA_RF_CNT_MASK 0x7f 72 #define SUN4I_FIFO_STA_RF_CNT_BITS 0 73 #define SUN4I_FIFO_STA_TF_CNT_MASK 0x7f 74 #define SUN4I_FIFO_STA_TF_CNT_BITS 16 75 76 struct sun4i_spi { 77 struct spi_master *master; 78 void __iomem *base_addr; 79 struct clk *hclk; 80 struct clk *mclk; 81 82 struct completion done; 83 84 const u8 *tx_buf; 85 u8 *rx_buf; 86 int len; 87 }; 88 89 static inline u32 sun4i_spi_read(struct sun4i_spi *sspi, u32 reg) 90 { 91 return readl(sspi->base_addr + reg); 92 } 93 94 static inline void sun4i_spi_write(struct sun4i_spi *sspi, u32 reg, u32 value) 95 { 96 writel(value, sspi->base_addr + reg); 97 } 98 99 static inline void sun4i_spi_drain_fifo(struct sun4i_spi *sspi, int len) 100 { 101 u32 reg, cnt; 102 u8 byte; 103 104 /* See how much data is available */ 105 reg = sun4i_spi_read(sspi, SUN4I_FIFO_STA_REG); 106 reg &= SUN4I_FIFO_STA_RF_CNT_MASK; 107 cnt = reg >> SUN4I_FIFO_STA_RF_CNT_BITS; 108 109 if (len > cnt) 110 len = cnt; 111 112 while (len--) { 113 byte = readb(sspi->base_addr + SUN4I_RXDATA_REG); 114 if (sspi->rx_buf) 115 *sspi->rx_buf++ = byte; 116 } 117 } 118 119 static inline void sun4i_spi_fill_fifo(struct sun4i_spi *sspi, int len) 120 { 121 u8 byte; 122 123 if (len > sspi->len) 124 len = sspi->len; 125 126 while (len--) { 127 byte = sspi->tx_buf ? *sspi->tx_buf++ : 0; 128 writeb(byte, sspi->base_addr + SUN4I_TXDATA_REG); 129 sspi->len--; 130 } 131 } 132 133 static void sun4i_spi_set_cs(struct spi_device *spi, bool enable) 134 { 135 struct sun4i_spi *sspi = spi_master_get_devdata(spi->master); 136 u32 reg; 137 138 reg = sun4i_spi_read(sspi, SUN4I_CTL_REG); 139 140 reg &= ~SUN4I_CTL_CS_MASK; 141 reg |= SUN4I_CTL_CS(spi->chip_select); 142 143 /* We want to control the chip select manually */ 144 reg |= SUN4I_CTL_CS_MANUAL; 145 146 if (enable) 147 reg |= SUN4I_CTL_CS_LEVEL; 148 else 149 reg &= ~SUN4I_CTL_CS_LEVEL; 150 151 /* 152 * Even though this looks irrelevant since we are supposed to 153 * be controlling the chip select manually, this bit also 154 * controls the levels of the chip select for inactive 155 * devices. 156 * 157 * If we don't set it, the chip select level will go low by 158 * default when the device is idle, which is not really 159 * expected in the common case where the chip select is active 160 * low. 161 */ 162 if (spi->mode & SPI_CS_HIGH) 163 reg &= ~SUN4I_CTL_CS_ACTIVE_LOW; 164 else 165 reg |= SUN4I_CTL_CS_ACTIVE_LOW; 166 167 sun4i_spi_write(sspi, SUN4I_CTL_REG, reg); 168 } 169 170 static int sun4i_spi_transfer_one(struct spi_master *master, 171 struct spi_device *spi, 172 struct spi_transfer *tfr) 173 { 174 struct sun4i_spi *sspi = spi_master_get_devdata(master); 175 unsigned int mclk_rate, div, timeout; 176 unsigned int tx_len = 0; 177 int ret = 0; 178 u32 reg; 179 180 /* We don't support transfer larger than the FIFO */ 181 if (tfr->len > SUN4I_FIFO_DEPTH) 182 return -EINVAL; 183 184 reinit_completion(&sspi->done); 185 sspi->tx_buf = tfr->tx_buf; 186 sspi->rx_buf = tfr->rx_buf; 187 sspi->len = tfr->len; 188 189 /* Clear pending interrupts */ 190 sun4i_spi_write(sspi, SUN4I_INT_STA_REG, ~0); 191 192 193 reg = sun4i_spi_read(sspi, SUN4I_CTL_REG); 194 195 /* Reset FIFOs */ 196 sun4i_spi_write(sspi, SUN4I_CTL_REG, 197 reg | SUN4I_CTL_RF_RST | SUN4I_CTL_TF_RST); 198 199 /* 200 * Setup the transfer control register: Chip Select, 201 * polarities, etc. 202 */ 203 if (spi->mode & SPI_CPOL) 204 reg |= SUN4I_CTL_CPOL; 205 else 206 reg &= ~SUN4I_CTL_CPOL; 207 208 if (spi->mode & SPI_CPHA) 209 reg |= SUN4I_CTL_CPHA; 210 else 211 reg &= ~SUN4I_CTL_CPHA; 212 213 if (spi->mode & SPI_LSB_FIRST) 214 reg |= SUN4I_CTL_LMTF; 215 else 216 reg &= ~SUN4I_CTL_LMTF; 217 218 219 /* 220 * If it's a TX only transfer, we don't want to fill the RX 221 * FIFO with bogus data 222 */ 223 if (sspi->rx_buf) 224 reg &= ~SUN4I_CTL_DHB; 225 else 226 reg |= SUN4I_CTL_DHB; 227 228 sun4i_spi_write(sspi, SUN4I_CTL_REG, reg); 229 230 /* Ensure that we have a parent clock fast enough */ 231 mclk_rate = clk_get_rate(sspi->mclk); 232 if (mclk_rate < (2 * tfr->speed_hz)) { 233 clk_set_rate(sspi->mclk, 2 * tfr->speed_hz); 234 mclk_rate = clk_get_rate(sspi->mclk); 235 } 236 237 /* 238 * Setup clock divider. 239 * 240 * We have two choices there. Either we can use the clock 241 * divide rate 1, which is calculated thanks to this formula: 242 * SPI_CLK = MOD_CLK / (2 ^ (cdr + 1)) 243 * Or we can use CDR2, which is calculated with the formula: 244 * SPI_CLK = MOD_CLK / (2 * (cdr + 1)) 245 * Wether we use the former or the latter is set through the 246 * DRS bit. 247 * 248 * First try CDR2, and if we can't reach the expected 249 * frequency, fall back to CDR1. 250 */ 251 div = mclk_rate / (2 * tfr->speed_hz); 252 if (div <= (SUN4I_CLK_CTL_CDR2_MASK + 1)) { 253 if (div > 0) 254 div--; 255 256 reg = SUN4I_CLK_CTL_CDR2(div) | SUN4I_CLK_CTL_DRS; 257 } else { 258 div = ilog2(mclk_rate) - ilog2(tfr->speed_hz); 259 reg = SUN4I_CLK_CTL_CDR1(div); 260 } 261 262 sun4i_spi_write(sspi, SUN4I_CLK_CTL_REG, reg); 263 264 /* Setup the transfer now... */ 265 if (sspi->tx_buf) 266 tx_len = tfr->len; 267 268 /* Setup the counters */ 269 sun4i_spi_write(sspi, SUN4I_BURST_CNT_REG, SUN4I_BURST_CNT(tfr->len)); 270 sun4i_spi_write(sspi, SUN4I_XMIT_CNT_REG, SUN4I_XMIT_CNT(tx_len)); 271 272 /* Fill the TX FIFO */ 273 sun4i_spi_fill_fifo(sspi, SUN4I_FIFO_DEPTH); 274 275 /* Enable the interrupts */ 276 sun4i_spi_write(sspi, SUN4I_INT_CTL_REG, SUN4I_INT_CTL_TC); 277 278 /* Start the transfer */ 279 reg = sun4i_spi_read(sspi, SUN4I_CTL_REG); 280 sun4i_spi_write(sspi, SUN4I_CTL_REG, reg | SUN4I_CTL_XCH); 281 282 timeout = wait_for_completion_timeout(&sspi->done, 283 msecs_to_jiffies(1000)); 284 if (!timeout) { 285 ret = -ETIMEDOUT; 286 goto out; 287 } 288 289 sun4i_spi_drain_fifo(sspi, SUN4I_FIFO_DEPTH); 290 291 out: 292 sun4i_spi_write(sspi, SUN4I_INT_CTL_REG, 0); 293 294 return ret; 295 } 296 297 static irqreturn_t sun4i_spi_handler(int irq, void *dev_id) 298 { 299 struct sun4i_spi *sspi = dev_id; 300 u32 status = sun4i_spi_read(sspi, SUN4I_INT_STA_REG); 301 302 /* Transfer complete */ 303 if (status & SUN4I_INT_CTL_TC) { 304 sun4i_spi_write(sspi, SUN4I_INT_STA_REG, SUN4I_INT_CTL_TC); 305 complete(&sspi->done); 306 return IRQ_HANDLED; 307 } 308 309 return IRQ_NONE; 310 } 311 312 static int sun4i_spi_runtime_resume(struct device *dev) 313 { 314 struct spi_master *master = dev_get_drvdata(dev); 315 struct sun4i_spi *sspi = spi_master_get_devdata(master); 316 int ret; 317 318 ret = clk_prepare_enable(sspi->hclk); 319 if (ret) { 320 dev_err(dev, "Couldn't enable AHB clock\n"); 321 goto out; 322 } 323 324 ret = clk_prepare_enable(sspi->mclk); 325 if (ret) { 326 dev_err(dev, "Couldn't enable module clock\n"); 327 goto err; 328 } 329 330 sun4i_spi_write(sspi, SUN4I_CTL_REG, 331 SUN4I_CTL_ENABLE | SUN4I_CTL_MASTER | SUN4I_CTL_TP); 332 333 return 0; 334 335 err: 336 clk_disable_unprepare(sspi->hclk); 337 out: 338 return ret; 339 } 340 341 static int sun4i_spi_runtime_suspend(struct device *dev) 342 { 343 struct spi_master *master = dev_get_drvdata(dev); 344 struct sun4i_spi *sspi = spi_master_get_devdata(master); 345 346 clk_disable_unprepare(sspi->mclk); 347 clk_disable_unprepare(sspi->hclk); 348 349 return 0; 350 } 351 352 static int sun4i_spi_probe(struct platform_device *pdev) 353 { 354 struct spi_master *master; 355 struct sun4i_spi *sspi; 356 struct resource *res; 357 int ret = 0, irq; 358 359 master = spi_alloc_master(&pdev->dev, sizeof(struct sun4i_spi)); 360 if (!master) { 361 dev_err(&pdev->dev, "Unable to allocate SPI Master\n"); 362 return -ENOMEM; 363 } 364 365 platform_set_drvdata(pdev, master); 366 sspi = spi_master_get_devdata(master); 367 368 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 369 sspi->base_addr = devm_ioremap_resource(&pdev->dev, res); 370 if (IS_ERR(sspi->base_addr)) { 371 ret = PTR_ERR(sspi->base_addr); 372 goto err_free_master; 373 } 374 375 irq = platform_get_irq(pdev, 0); 376 if (irq < 0) { 377 dev_err(&pdev->dev, "No spi IRQ specified\n"); 378 ret = -ENXIO; 379 goto err_free_master; 380 } 381 382 ret = devm_request_irq(&pdev->dev, irq, sun4i_spi_handler, 383 0, "sun4i-spi", sspi); 384 if (ret) { 385 dev_err(&pdev->dev, "Cannot request IRQ\n"); 386 goto err_free_master; 387 } 388 389 sspi->master = master; 390 master->set_cs = sun4i_spi_set_cs; 391 master->transfer_one = sun4i_spi_transfer_one; 392 master->num_chipselect = 4; 393 master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH | SPI_LSB_FIRST; 394 master->bits_per_word_mask = SPI_BPW_MASK(8); 395 master->dev.of_node = pdev->dev.of_node; 396 master->auto_runtime_pm = true; 397 398 sspi->hclk = devm_clk_get(&pdev->dev, "ahb"); 399 if (IS_ERR(sspi->hclk)) { 400 dev_err(&pdev->dev, "Unable to acquire AHB clock\n"); 401 ret = PTR_ERR(sspi->hclk); 402 goto err_free_master; 403 } 404 405 sspi->mclk = devm_clk_get(&pdev->dev, "mod"); 406 if (IS_ERR(sspi->mclk)) { 407 dev_err(&pdev->dev, "Unable to acquire module clock\n"); 408 ret = PTR_ERR(sspi->mclk); 409 goto err_free_master; 410 } 411 412 init_completion(&sspi->done); 413 414 /* 415 * This wake-up/shutdown pattern is to be able to have the 416 * device woken up, even if runtime_pm is disabled 417 */ 418 ret = sun4i_spi_runtime_resume(&pdev->dev); 419 if (ret) { 420 dev_err(&pdev->dev, "Couldn't resume the device\n"); 421 goto err_free_master; 422 } 423 424 pm_runtime_set_active(&pdev->dev); 425 pm_runtime_enable(&pdev->dev); 426 pm_runtime_idle(&pdev->dev); 427 428 ret = devm_spi_register_master(&pdev->dev, master); 429 if (ret) { 430 dev_err(&pdev->dev, "cannot register SPI master\n"); 431 goto err_pm_disable; 432 } 433 434 return 0; 435 436 err_pm_disable: 437 pm_runtime_disable(&pdev->dev); 438 sun4i_spi_runtime_suspend(&pdev->dev); 439 err_free_master: 440 spi_master_put(master); 441 return ret; 442 } 443 444 static int sun4i_spi_remove(struct platform_device *pdev) 445 { 446 pm_runtime_disable(&pdev->dev); 447 448 return 0; 449 } 450 451 static const struct of_device_id sun4i_spi_match[] = { 452 { .compatible = "allwinner,sun4i-a10-spi", }, 453 {} 454 }; 455 MODULE_DEVICE_TABLE(of, sun4i_spi_match); 456 457 static const struct dev_pm_ops sun4i_spi_pm_ops = { 458 .runtime_resume = sun4i_spi_runtime_resume, 459 .runtime_suspend = sun4i_spi_runtime_suspend, 460 }; 461 462 static struct platform_driver sun4i_spi_driver = { 463 .probe = sun4i_spi_probe, 464 .remove = sun4i_spi_remove, 465 .driver = { 466 .name = "sun4i-spi", 467 .of_match_table = sun4i_spi_match, 468 .pm = &sun4i_spi_pm_ops, 469 }, 470 }; 471 module_platform_driver(sun4i_spi_driver); 472 473 MODULE_AUTHOR("Pan Nan <pannan@allwinnertech.com>"); 474 MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com>"); 475 MODULE_DESCRIPTION("Allwinner A1X/A20 SPI controller driver"); 476 MODULE_LICENSE("GPL"); 477