soft_spi.c 6.0 KB

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  1. // SPDX-License-Identifier: GPL-2.0+
  2. /*
  3. * Copyright (c) 2014 Google, Inc
  4. *
  5. * (C) Copyright 2002
  6. * Gerald Van Baren, Custom IDEAS, vanbaren@cideas.com.
  7. *
  8. * Influenced by code from:
  9. * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
  10. */
  11. #include <common.h>
  12. #include <dm.h>
  13. #include <errno.h>
  14. #include <fdtdec.h>
  15. #include <malloc.h>
  16. #include <spi.h>
  17. #include <asm/gpio.h>
  18. DECLARE_GLOBAL_DATA_PTR;
  19. struct soft_spi_platdata {
  20. struct gpio_desc cs;
  21. struct gpio_desc sclk;
  22. struct gpio_desc mosi;
  23. struct gpio_desc miso;
  24. int spi_delay_us;
  25. int flags;
  26. };
  27. #define SPI_MASTER_NO_RX BIT(0)
  28. #define SPI_MASTER_NO_TX BIT(1)
  29. struct soft_spi_priv {
  30. unsigned int mode;
  31. };
  32. static int soft_spi_scl(struct udevice *dev, int bit)
  33. {
  34. struct udevice *bus = dev_get_parent(dev);
  35. struct soft_spi_platdata *plat = dev_get_platdata(bus);
  36. dm_gpio_set_value(&plat->sclk, bit);
  37. return 0;
  38. }
  39. static int soft_spi_sda(struct udevice *dev, int bit)
  40. {
  41. struct udevice *bus = dev_get_parent(dev);
  42. struct soft_spi_platdata *plat = dev_get_platdata(bus);
  43. dm_gpio_set_value(&plat->mosi, bit);
  44. return 0;
  45. }
  46. static int soft_spi_cs_activate(struct udevice *dev)
  47. {
  48. struct udevice *bus = dev_get_parent(dev);
  49. struct soft_spi_platdata *plat = dev_get_platdata(bus);
  50. dm_gpio_set_value(&plat->cs, 0);
  51. dm_gpio_set_value(&plat->sclk, 0);
  52. dm_gpio_set_value(&plat->cs, 1);
  53. return 0;
  54. }
  55. static int soft_spi_cs_deactivate(struct udevice *dev)
  56. {
  57. struct udevice *bus = dev_get_parent(dev);
  58. struct soft_spi_platdata *plat = dev_get_platdata(bus);
  59. dm_gpio_set_value(&plat->cs, 0);
  60. return 0;
  61. }
  62. static int soft_spi_claim_bus(struct udevice *dev)
  63. {
  64. /*
  65. * Make sure the SPI clock is in idle state as defined for
  66. * this slave.
  67. */
  68. return soft_spi_scl(dev, 0);
  69. }
  70. static int soft_spi_release_bus(struct udevice *dev)
  71. {
  72. /* Nothing to do */
  73. return 0;
  74. }
  75. /*-----------------------------------------------------------------------
  76. * SPI transfer
  77. *
  78. * This writes "bitlen" bits out the SPI MOSI port and simultaneously clocks
  79. * "bitlen" bits in the SPI MISO port. That's just the way SPI works.
  80. *
  81. * The source of the outgoing bits is the "dout" parameter and the
  82. * destination of the input bits is the "din" parameter. Note that "dout"
  83. * and "din" can point to the same memory location, in which case the
  84. * input data overwrites the output data (since both are buffered by
  85. * temporary variables, this is OK).
  86. */
  87. static int soft_spi_xfer(struct udevice *dev, unsigned int bitlen,
  88. const void *dout, void *din, unsigned long flags)
  89. {
  90. struct udevice *bus = dev_get_parent(dev);
  91. struct soft_spi_priv *priv = dev_get_priv(bus);
  92. struct soft_spi_platdata *plat = dev_get_platdata(bus);
  93. uchar tmpdin = 0;
  94. uchar tmpdout = 0;
  95. const u8 *txd = dout;
  96. u8 *rxd = din;
  97. int cpha = priv->mode & SPI_CPHA;
  98. unsigned int j;
  99. debug("spi_xfer: slave %s:%s dout %08X din %08X bitlen %u\n",
  100. dev->parent->name, dev->name, *(uint *)txd, *(uint *)rxd,
  101. bitlen);
  102. if (flags & SPI_XFER_BEGIN)
  103. soft_spi_cs_activate(dev);
  104. for (j = 0; j < bitlen; j++) {
  105. /*
  106. * Check if it is time to work on a new byte.
  107. */
  108. if ((j % 8) == 0) {
  109. if (txd)
  110. tmpdout = *txd++;
  111. else
  112. tmpdout = 0;
  113. if (j != 0) {
  114. if (rxd)
  115. *rxd++ = tmpdin;
  116. }
  117. tmpdin = 0;
  118. }
  119. if (!cpha)
  120. soft_spi_scl(dev, 0);
  121. if ((plat->flags & SPI_MASTER_NO_TX) == 0)
  122. soft_spi_sda(dev, !!(tmpdout & 0x80));
  123. udelay(plat->spi_delay_us);
  124. if (cpha)
  125. soft_spi_scl(dev, 0);
  126. else
  127. soft_spi_scl(dev, 1);
  128. tmpdin <<= 1;
  129. if ((plat->flags & SPI_MASTER_NO_RX) == 0)
  130. tmpdin |= dm_gpio_get_value(&plat->miso);
  131. tmpdout <<= 1;
  132. udelay(plat->spi_delay_us);
  133. if (cpha)
  134. soft_spi_scl(dev, 1);
  135. }
  136. /*
  137. * If the number of bits isn't a multiple of 8, shift the last
  138. * bits over to left-justify them. Then store the last byte
  139. * read in.
  140. */
  141. if (rxd) {
  142. if ((bitlen % 8) != 0)
  143. tmpdin <<= 8 - (bitlen % 8);
  144. *rxd++ = tmpdin;
  145. }
  146. if (flags & SPI_XFER_END)
  147. soft_spi_cs_deactivate(dev);
  148. return 0;
  149. }
  150. static int soft_spi_set_speed(struct udevice *dev, unsigned int speed)
  151. {
  152. /* Accept any speed */
  153. return 0;
  154. }
  155. static int soft_spi_set_mode(struct udevice *dev, unsigned int mode)
  156. {
  157. struct soft_spi_priv *priv = dev_get_priv(dev);
  158. priv->mode = mode;
  159. return 0;
  160. }
  161. static const struct dm_spi_ops soft_spi_ops = {
  162. .claim_bus = soft_spi_claim_bus,
  163. .release_bus = soft_spi_release_bus,
  164. .xfer = soft_spi_xfer,
  165. .set_speed = soft_spi_set_speed,
  166. .set_mode = soft_spi_set_mode,
  167. };
  168. static int soft_spi_ofdata_to_platdata(struct udevice *dev)
  169. {
  170. struct soft_spi_platdata *plat = dev->platdata;
  171. const void *blob = gd->fdt_blob;
  172. int node = dev_of_offset(dev);
  173. plat->spi_delay_us = fdtdec_get_int(blob, node, "spi-delay-us", 0);
  174. return 0;
  175. }
  176. static int soft_spi_probe(struct udevice *dev)
  177. {
  178. struct spi_slave *slave = dev_get_parent_priv(dev);
  179. struct soft_spi_platdata *plat = dev->platdata;
  180. int cs_flags, clk_flags;
  181. int ret;
  182. cs_flags = (slave && slave->mode & SPI_CS_HIGH) ? 0 : GPIOD_ACTIVE_LOW;
  183. clk_flags = (slave && slave->mode & SPI_CPOL) ? GPIOD_ACTIVE_LOW : 0;
  184. if (gpio_request_by_name(dev, "cs-gpios", 0, &plat->cs,
  185. GPIOD_IS_OUT | cs_flags) ||
  186. gpio_request_by_name(dev, "gpio-sck", 0, &plat->sclk,
  187. GPIOD_IS_OUT | clk_flags))
  188. return -EINVAL;
  189. ret = gpio_request_by_name(dev, "gpio-mosi", 0, &plat->mosi,
  190. GPIOD_IS_OUT | GPIOD_IS_OUT_ACTIVE);
  191. if (ret)
  192. plat->flags |= SPI_MASTER_NO_TX;
  193. ret = gpio_request_by_name(dev, "gpio-miso", 0, &plat->miso,
  194. GPIOD_IS_IN);
  195. if (ret)
  196. plat->flags |= SPI_MASTER_NO_RX;
  197. if ((plat->flags & (SPI_MASTER_NO_RX | SPI_MASTER_NO_TX)) ==
  198. (SPI_MASTER_NO_RX | SPI_MASTER_NO_TX))
  199. return -EINVAL;
  200. return 0;
  201. }
  202. static const struct udevice_id soft_spi_ids[] = {
  203. { .compatible = "spi-gpio" },
  204. { }
  205. };
  206. U_BOOT_DRIVER(soft_spi) = {
  207. .name = "soft_spi",
  208. .id = UCLASS_SPI,
  209. .of_match = soft_spi_ids,
  210. .ops = &soft_spi_ops,
  211. .ofdata_to_platdata = soft_spi_ofdata_to_platdata,
  212. .platdata_auto_alloc_size = sizeof(struct soft_spi_platdata),
  213. .priv_auto_alloc_size = sizeof(struct soft_spi_priv),
  214. .probe = soft_spi_probe,
  215. };