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