1 /* 2 * OpenCores tiny SPI master driver 3 * 4 * http://opencores.org/project,tiny_spi 5 * 6 * Copyright (C) 2011 Thomas Chou <thomas@wytron.com.tw> 7 * 8 * Based on spi_s3c24xx.c, which is: 9 * Copyright (c) 2006 Ben Dooks 10 * Copyright (c) 2006 Simtec Electronics 11 * Ben Dooks <ben@simtec.co.uk> 12 * 13 * This program is free software; you can redistribute it and/or modify 14 * it under the terms of the GNU General Public License version 2 as 15 * published by the Free Software Foundation. 16 */ 17 18 #include <linux/init.h> 19 #include <linux/interrupt.h> 20 #include <linux/errno.h> 21 #include <linux/module.h> 22 #include <linux/platform_device.h> 23 #include <linux/spi/spi.h> 24 #include <linux/spi/spi_bitbang.h> 25 #include <linux/spi/spi_oc_tiny.h> 26 #include <linux/io.h> 27 #include <linux/gpio.h> 28 #include <linux/of.h> 29 30 #define DRV_NAME "spi_oc_tiny" 31 32 #define TINY_SPI_RXDATA 0 33 #define TINY_SPI_TXDATA 4 34 #define TINY_SPI_STATUS 8 35 #define TINY_SPI_CONTROL 12 36 #define TINY_SPI_BAUD 16 37 38 #define TINY_SPI_STATUS_TXE 0x1 39 #define TINY_SPI_STATUS_TXR 0x2 40 41 struct tiny_spi { 42 /* bitbang has to be first */ 43 struct spi_bitbang bitbang; 44 struct completion done; 45 46 void __iomem *base; 47 int irq; 48 unsigned int freq; 49 unsigned int baudwidth; 50 unsigned int baud; 51 unsigned int speed_hz; 52 unsigned int mode; 53 unsigned int len; 54 unsigned int txc, rxc; 55 const u8 *txp; 56 u8 *rxp; 57 int gpio_cs_count; 58 int *gpio_cs; 59 }; 60 61 static inline struct tiny_spi *tiny_spi_to_hw(struct spi_device *sdev) 62 { 63 return spi_master_get_devdata(sdev->master); 64 } 65 66 static unsigned int tiny_spi_baud(struct spi_device *spi, unsigned int hz) 67 { 68 struct tiny_spi *hw = tiny_spi_to_hw(spi); 69 70 return min(DIV_ROUND_UP(hw->freq, hz * 2), (1U << hw->baudwidth)) - 1; 71 } 72 73 static void tiny_spi_chipselect(struct spi_device *spi, int is_active) 74 { 75 struct tiny_spi *hw = tiny_spi_to_hw(spi); 76 77 if (hw->gpio_cs_count > 0) { 78 gpio_set_value(hw->gpio_cs[spi->chip_select], 79 (spi->mode & SPI_CS_HIGH) ? is_active : !is_active); 80 } 81 } 82 83 static int tiny_spi_setup_transfer(struct spi_device *spi, 84 struct spi_transfer *t) 85 { 86 struct tiny_spi *hw = tiny_spi_to_hw(spi); 87 unsigned int baud = hw->baud; 88 89 if (t) { 90 if (t->speed_hz && t->speed_hz != hw->speed_hz) 91 baud = tiny_spi_baud(spi, t->speed_hz); 92 } 93 writel(baud, hw->base + TINY_SPI_BAUD); 94 writel(hw->mode, hw->base + TINY_SPI_CONTROL); 95 return 0; 96 } 97 98 static int tiny_spi_setup(struct spi_device *spi) 99 { 100 struct tiny_spi *hw = tiny_spi_to_hw(spi); 101 102 if (spi->max_speed_hz != hw->speed_hz) { 103 hw->speed_hz = spi->max_speed_hz; 104 hw->baud = tiny_spi_baud(spi, hw->speed_hz); 105 } 106 hw->mode = spi->mode & (SPI_CPOL | SPI_CPHA); 107 return 0; 108 } 109 110 static inline void tiny_spi_wait_txr(struct tiny_spi *hw) 111 { 112 while (!(readb(hw->base + TINY_SPI_STATUS) & 113 TINY_SPI_STATUS_TXR)) 114 cpu_relax(); 115 } 116 117 static inline void tiny_spi_wait_txe(struct tiny_spi *hw) 118 { 119 while (!(readb(hw->base + TINY_SPI_STATUS) & 120 TINY_SPI_STATUS_TXE)) 121 cpu_relax(); 122 } 123 124 static int tiny_spi_txrx_bufs(struct spi_device *spi, struct spi_transfer *t) 125 { 126 struct tiny_spi *hw = tiny_spi_to_hw(spi); 127 const u8 *txp = t->tx_buf; 128 u8 *rxp = t->rx_buf; 129 unsigned int i; 130 131 if (hw->irq >= 0) { 132 /* use interrupt driven data transfer */ 133 hw->len = t->len; 134 hw->txp = t->tx_buf; 135 hw->rxp = t->rx_buf; 136 hw->txc = 0; 137 hw->rxc = 0; 138 139 /* send the first byte */ 140 if (t->len > 1) { 141 writeb(hw->txp ? *hw->txp++ : 0, 142 hw->base + TINY_SPI_TXDATA); 143 hw->txc++; 144 writeb(hw->txp ? *hw->txp++ : 0, 145 hw->base + TINY_SPI_TXDATA); 146 hw->txc++; 147 writeb(TINY_SPI_STATUS_TXR, hw->base + TINY_SPI_STATUS); 148 } else { 149 writeb(hw->txp ? *hw->txp++ : 0, 150 hw->base + TINY_SPI_TXDATA); 151 hw->txc++; 152 writeb(TINY_SPI_STATUS_TXE, hw->base + TINY_SPI_STATUS); 153 } 154 155 wait_for_completion(&hw->done); 156 } else { 157 /* we need to tighten the transfer loop */ 158 writeb(txp ? *txp++ : 0, hw->base + TINY_SPI_TXDATA); 159 for (i = 1; i < t->len; i++) { 160 writeb(txp ? *txp++ : 0, hw->base + TINY_SPI_TXDATA); 161 162 if (rxp || (i != t->len - 1)) 163 tiny_spi_wait_txr(hw); 164 if (rxp) 165 *rxp++ = readb(hw->base + TINY_SPI_TXDATA); 166 } 167 tiny_spi_wait_txe(hw); 168 if (rxp) 169 *rxp++ = readb(hw->base + TINY_SPI_RXDATA); 170 } 171 172 return t->len; 173 } 174 175 static irqreturn_t tiny_spi_irq(int irq, void *dev) 176 { 177 struct tiny_spi *hw = dev; 178 179 writeb(0, hw->base + TINY_SPI_STATUS); 180 if (hw->rxc + 1 == hw->len) { 181 if (hw->rxp) 182 *hw->rxp++ = readb(hw->base + TINY_SPI_RXDATA); 183 hw->rxc++; 184 complete(&hw->done); 185 } else { 186 if (hw->rxp) 187 *hw->rxp++ = readb(hw->base + TINY_SPI_TXDATA); 188 hw->rxc++; 189 if (hw->txc < hw->len) { 190 writeb(hw->txp ? *hw->txp++ : 0, 191 hw->base + TINY_SPI_TXDATA); 192 hw->txc++; 193 writeb(TINY_SPI_STATUS_TXR, 194 hw->base + TINY_SPI_STATUS); 195 } else { 196 writeb(TINY_SPI_STATUS_TXE, 197 hw->base + TINY_SPI_STATUS); 198 } 199 } 200 return IRQ_HANDLED; 201 } 202 203 #ifdef CONFIG_OF 204 #include <linux/of_gpio.h> 205 206 static int tiny_spi_of_probe(struct platform_device *pdev) 207 { 208 struct tiny_spi *hw = platform_get_drvdata(pdev); 209 struct device_node *np = pdev->dev.of_node; 210 unsigned int i; 211 const __be32 *val; 212 int len; 213 214 if (!np) 215 return 0; 216 hw->gpio_cs_count = of_gpio_count(np); 217 if (hw->gpio_cs_count > 0) { 218 hw->gpio_cs = devm_kzalloc(&pdev->dev, 219 hw->gpio_cs_count * sizeof(unsigned int), 220 GFP_KERNEL); 221 if (!hw->gpio_cs) 222 return -ENOMEM; 223 } 224 for (i = 0; i < hw->gpio_cs_count; i++) { 225 hw->gpio_cs[i] = of_get_gpio_flags(np, i, NULL); 226 if (hw->gpio_cs[i] < 0) 227 return -ENODEV; 228 } 229 hw->bitbang.master->dev.of_node = pdev->dev.of_node; 230 val = of_get_property(pdev->dev.of_node, 231 "clock-frequency", &len); 232 if (val && len >= sizeof(__be32)) 233 hw->freq = be32_to_cpup(val); 234 val = of_get_property(pdev->dev.of_node, "baud-width", &len); 235 if (val && len >= sizeof(__be32)) 236 hw->baudwidth = be32_to_cpup(val); 237 return 0; 238 } 239 #else /* !CONFIG_OF */ 240 static int tiny_spi_of_probe(struct platform_device *pdev) 241 { 242 return 0; 243 } 244 #endif /* CONFIG_OF */ 245 246 static int tiny_spi_probe(struct platform_device *pdev) 247 { 248 struct tiny_spi_platform_data *platp = dev_get_platdata(&pdev->dev); 249 struct tiny_spi *hw; 250 struct spi_master *master; 251 struct resource *res; 252 unsigned int i; 253 int err = -ENODEV; 254 255 master = spi_alloc_master(&pdev->dev, sizeof(struct tiny_spi)); 256 if (!master) 257 return err; 258 259 /* setup the master state. */ 260 master->bus_num = pdev->id; 261 master->num_chipselect = 255; 262 master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH; 263 master->setup = tiny_spi_setup; 264 265 hw = spi_master_get_devdata(master); 266 platform_set_drvdata(pdev, hw); 267 268 /* setup the state for the bitbang driver */ 269 hw->bitbang.master = master; 270 if (!hw->bitbang.master) 271 return err; 272 hw->bitbang.setup_transfer = tiny_spi_setup_transfer; 273 hw->bitbang.chipselect = tiny_spi_chipselect; 274 hw->bitbang.txrx_bufs = tiny_spi_txrx_bufs; 275 276 /* find and map our resources */ 277 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 278 hw->base = devm_ioremap_resource(&pdev->dev, res); 279 if (IS_ERR(hw->base)) { 280 err = PTR_ERR(hw->base); 281 goto exit; 282 } 283 /* irq is optional */ 284 hw->irq = platform_get_irq(pdev, 0); 285 if (hw->irq >= 0) { 286 init_completion(&hw->done); 287 err = devm_request_irq(&pdev->dev, hw->irq, tiny_spi_irq, 0, 288 pdev->name, hw); 289 if (err) 290 goto exit; 291 } 292 /* find platform data */ 293 if (platp) { 294 hw->gpio_cs_count = platp->gpio_cs_count; 295 hw->gpio_cs = platp->gpio_cs; 296 if (platp->gpio_cs_count && !platp->gpio_cs) { 297 err = -EBUSY; 298 goto exit; 299 } 300 hw->freq = platp->freq; 301 hw->baudwidth = platp->baudwidth; 302 } else { 303 err = tiny_spi_of_probe(pdev); 304 if (err) 305 goto exit; 306 } 307 for (i = 0; i < hw->gpio_cs_count; i++) { 308 err = gpio_request(hw->gpio_cs[i], dev_name(&pdev->dev)); 309 if (err) 310 goto exit_gpio; 311 gpio_direction_output(hw->gpio_cs[i], 1); 312 } 313 hw->bitbang.master->num_chipselect = max(1, hw->gpio_cs_count); 314 315 /* register our spi controller */ 316 err = spi_bitbang_start(&hw->bitbang); 317 if (err) 318 goto exit; 319 dev_info(&pdev->dev, "base %p, irq %d\n", hw->base, hw->irq); 320 321 return 0; 322 323 exit_gpio: 324 while (i-- > 0) 325 gpio_free(hw->gpio_cs[i]); 326 exit: 327 spi_master_put(master); 328 return err; 329 } 330 331 static int tiny_spi_remove(struct platform_device *pdev) 332 { 333 struct tiny_spi *hw = platform_get_drvdata(pdev); 334 struct spi_master *master = hw->bitbang.master; 335 unsigned int i; 336 337 spi_bitbang_stop(&hw->bitbang); 338 for (i = 0; i < hw->gpio_cs_count; i++) 339 gpio_free(hw->gpio_cs[i]); 340 spi_master_put(master); 341 return 0; 342 } 343 344 #ifdef CONFIG_OF 345 static const struct of_device_id tiny_spi_match[] = { 346 { .compatible = "opencores,tiny-spi-rtlsvn2", }, 347 {}, 348 }; 349 MODULE_DEVICE_TABLE(of, tiny_spi_match); 350 #endif /* CONFIG_OF */ 351 352 static struct platform_driver tiny_spi_driver = { 353 .probe = tiny_spi_probe, 354 .remove = tiny_spi_remove, 355 .driver = { 356 .name = DRV_NAME, 357 .owner = THIS_MODULE, 358 .pm = NULL, 359 .of_match_table = of_match_ptr(tiny_spi_match), 360 }, 361 }; 362 module_platform_driver(tiny_spi_driver); 363 364 MODULE_DESCRIPTION("OpenCores tiny SPI driver"); 365 MODULE_AUTHOR("Thomas Chou <thomas@wytron.com.tw>"); 366 MODULE_LICENSE("GPL"); 367 MODULE_ALIAS("platform:" DRV_NAME); 368