1 // SPDX-License-Identifier: GPL-2.0+
3 * Copyright (c) 2014 Google, Inc
6 * Gerald Van Baren, Custom IDEAS, vanbaren@cideas.com.
8 * Influenced by code from:
9 * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
20 #include <linux/delay.h>
22 DECLARE_GLOBAL_DATA_PTR;
24 struct soft_spi_platdata {
26 struct gpio_desc sclk;
27 struct gpio_desc mosi;
28 struct gpio_desc miso;
33 #define SPI_MASTER_NO_RX BIT(0)
34 #define SPI_MASTER_NO_TX BIT(1)
36 struct soft_spi_priv {
40 static int soft_spi_scl(struct udevice *dev, int bit)
42 struct udevice *bus = dev_get_parent(dev);
43 struct soft_spi_platdata *plat = dev_get_platdata(bus);
45 dm_gpio_set_value(&plat->sclk, bit);
50 static int soft_spi_sda(struct udevice *dev, int bit)
52 struct udevice *bus = dev_get_parent(dev);
53 struct soft_spi_platdata *plat = dev_get_platdata(bus);
55 dm_gpio_set_value(&plat->mosi, bit);
60 static int soft_spi_cs_activate(struct udevice *dev)
62 struct udevice *bus = dev_get_parent(dev);
63 struct soft_spi_platdata *plat = dev_get_platdata(bus);
65 dm_gpio_set_value(&plat->cs, 0);
66 dm_gpio_set_value(&plat->sclk, 0);
67 dm_gpio_set_value(&plat->cs, 1);
72 static int soft_spi_cs_deactivate(struct udevice *dev)
74 struct udevice *bus = dev_get_parent(dev);
75 struct soft_spi_platdata *plat = dev_get_platdata(bus);
77 dm_gpio_set_value(&plat->cs, 0);
82 static int soft_spi_claim_bus(struct udevice *dev)
85 * Make sure the SPI clock is in idle state as defined for
88 return soft_spi_scl(dev, 0);
91 static int soft_spi_release_bus(struct udevice *dev)
97 /*-----------------------------------------------------------------------
100 * This writes "bitlen" bits out the SPI MOSI port and simultaneously clocks
101 * "bitlen" bits in the SPI MISO port. That's just the way SPI works.
103 * The source of the outgoing bits is the "dout" parameter and the
104 * destination of the input bits is the "din" parameter. Note that "dout"
105 * and "din" can point to the same memory location, in which case the
106 * input data overwrites the output data (since both are buffered by
107 * temporary variables, this is OK).
109 static int soft_spi_xfer(struct udevice *dev, unsigned int bitlen,
110 const void *dout, void *din, unsigned long flags)
112 struct udevice *bus = dev_get_parent(dev);
113 struct soft_spi_priv *priv = dev_get_priv(bus);
114 struct soft_spi_platdata *plat = dev_get_platdata(bus);
117 const u8 *txd = dout;
119 int cpha = priv->mode & SPI_CPHA;
122 debug("spi_xfer: slave %s:%s dout %08X din %08X bitlen %u\n",
123 dev->parent->name, dev->name, *(uint *)txd, *(uint *)rxd,
126 if (flags & SPI_XFER_BEGIN)
127 soft_spi_cs_activate(dev);
129 for (j = 0; j < bitlen; j++) {
131 * Check if it is time to work on a new byte.
146 soft_spi_scl(dev, 0);
147 if ((plat->flags & SPI_MASTER_NO_TX) == 0)
148 soft_spi_sda(dev, !!(tmpdout & 0x80));
149 udelay(plat->spi_delay_us);
151 soft_spi_scl(dev, 0);
153 soft_spi_scl(dev, 1);
155 if ((plat->flags & SPI_MASTER_NO_RX) == 0)
156 tmpdin |= dm_gpio_get_value(&plat->miso);
158 udelay(plat->spi_delay_us);
160 soft_spi_scl(dev, 1);
163 * If the number of bits isn't a multiple of 8, shift the last
164 * bits over to left-justify them. Then store the last byte
168 if ((bitlen % 8) != 0)
169 tmpdin <<= 8 - (bitlen % 8);
173 if (flags & SPI_XFER_END)
174 soft_spi_cs_deactivate(dev);
179 static int soft_spi_set_speed(struct udevice *dev, unsigned int speed)
181 /* Accept any speed */
185 static int soft_spi_set_mode(struct udevice *dev, unsigned int mode)
187 struct soft_spi_priv *priv = dev_get_priv(dev);
194 static const struct dm_spi_ops soft_spi_ops = {
195 .claim_bus = soft_spi_claim_bus,
196 .release_bus = soft_spi_release_bus,
197 .xfer = soft_spi_xfer,
198 .set_speed = soft_spi_set_speed,
199 .set_mode = soft_spi_set_mode,
202 static int soft_spi_ofdata_to_platdata(struct udevice *dev)
204 struct soft_spi_platdata *plat = dev->platdata;
205 const void *blob = gd->fdt_blob;
206 int node = dev_of_offset(dev);
208 plat->spi_delay_us = fdtdec_get_int(blob, node, "spi-delay-us", 0);
213 static int soft_spi_probe(struct udevice *dev)
215 struct spi_slave *slave = dev_get_parent_priv(dev);
216 struct soft_spi_platdata *plat = dev->platdata;
217 int cs_flags, clk_flags;
220 cs_flags = (slave && slave->mode & SPI_CS_HIGH) ? 0 : GPIOD_ACTIVE_LOW;
221 clk_flags = (slave && slave->mode & SPI_CPOL) ? GPIOD_ACTIVE_LOW : 0;
223 if (gpio_request_by_name(dev, "cs-gpios", 0, &plat->cs,
224 GPIOD_IS_OUT | cs_flags) ||
225 gpio_request_by_name(dev, "gpio-sck", 0, &plat->sclk,
226 GPIOD_IS_OUT | clk_flags))
229 ret = gpio_request_by_name(dev, "gpio-mosi", 0, &plat->mosi,
230 GPIOD_IS_OUT | GPIOD_IS_OUT_ACTIVE);
232 plat->flags |= SPI_MASTER_NO_TX;
234 ret = gpio_request_by_name(dev, "gpio-miso", 0, &plat->miso,
237 plat->flags |= SPI_MASTER_NO_RX;
239 if ((plat->flags & (SPI_MASTER_NO_RX | SPI_MASTER_NO_TX)) ==
240 (SPI_MASTER_NO_RX | SPI_MASTER_NO_TX))
246 static const struct udevice_id soft_spi_ids[] = {
247 { .compatible = "spi-gpio" },
251 U_BOOT_DRIVER(soft_spi) = {
254 .of_match = soft_spi_ids,
255 .ops = &soft_spi_ops,
256 .ofdata_to_platdata = soft_spi_ofdata_to_platdata,
257 .platdata_auto_alloc_size = sizeof(struct soft_spi_platdata),
258 .priv_auto_alloc_size = sizeof(struct soft_spi_priv),
259 .probe = soft_spi_probe,