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/*
* Copyright (c) 2014 Google, Inc
*
* (C) Copyright 2002
* Gerald Van Baren, Custom IDEAS, vanbaren@cideas.com.
*
* Influenced by code from:
* Wolfgang Denk, DENX Software Engineering, wd@denx.de.
*
* SPDX-License-Identifier: GPL-2.0+
*/
#include <common.h>
#include <dm.h>
#include <errno.h>
#include <fdtdec.h>
#include <malloc.h>
#include <spi.h>
#include <asm/gpio.h>
DECLARE_GLOBAL_DATA_PTR;
struct soft_spi_platdata {
struct gpio_desc cs;
struct gpio_desc sclk;
struct gpio_desc mosi;
struct gpio_desc miso;
int spi_delay_us;
};
struct soft_spi_priv {
unsigned int mode;
};
static int soft_spi_scl(struct udevice *dev, int bit)
{
struct soft_spi_platdata *plat = dev->platdata;
dm_gpio_set_value(&plat->sclk, bit);
return 0;
}
static int soft_spi_sda(struct udevice *dev, int bit)
{
struct soft_spi_platdata *plat = dev->platdata;
dm_gpio_set_value(&plat->mosi, bit);
return 0;
}
static int soft_spi_cs_activate(struct udevice *dev)
{
struct soft_spi_platdata *plat = dev->platdata;
dm_gpio_set_value(&plat->cs, 0);
dm_gpio_set_value(&plat->sclk, 0);
dm_gpio_set_value(&plat->cs, 1);
return 0;
}
static int soft_spi_cs_deactivate(struct udevice *dev)
{
struct soft_spi_platdata *plat = dev->platdata;
dm_gpio_set_value(&plat->cs, 0);
return 0;
}
static int soft_spi_claim_bus(struct udevice *dev)
{
/*
* Make sure the SPI clock is in idle state as defined for
* this slave.
*/
return soft_spi_scl(dev, 0);
}
static int soft_spi_release_bus(struct udevice *dev)
{
/* Nothing to do */
return 0;
}
/*-----------------------------------------------------------------------
* SPI transfer
*
* This writes "bitlen" bits out the SPI MOSI port and simultaneously clocks
* "bitlen" bits in the SPI MISO port. That's just the way SPI works.
*
* The source of the outgoing bits is the "dout" parameter and the
* destination of the input bits is the "din" parameter. Note that "dout"
* and "din" can point to the same memory location, in which case the
* input data overwrites the output data (since both are buffered by
* temporary variables, this is OK).
*/
static int soft_spi_xfer(struct udevice *dev, unsigned int bitlen,
const void *dout, void *din, unsigned long flags)
{
struct soft_spi_priv *priv = dev_get_priv(dev);
struct soft_spi_platdata *plat = dev->platdata;
uchar tmpdin = 0;
uchar tmpdout = 0;
const u8 *txd = dout;
u8 *rxd = din;
int cpha = priv->mode & SPI_CPHA;
unsigned int j;
debug("spi_xfer: slave %s:%s dout %08X din %08X bitlen %u\n",
dev->parent->name, dev->name, *(uint *)txd, *(uint *)rxd,
bitlen);
if (flags & SPI_XFER_BEGIN)
soft_spi_cs_activate(dev);
for (j = 0; j < bitlen; j++) {
/*
* Check if it is time to work on a new byte.
*/
if ((j % 8) == 0) {
if (txd)
tmpdout = *txd++;
else
tmpdout = 0;
if (j != 0) {
if (rxd)
*rxd++ = tmpdin;
}
tmpdin = 0;
}
if (!cpha)
soft_spi_scl(dev, 0);
soft_spi_sda(dev, tmpdout & 0x80);
udelay(plat->spi_delay_us);
if (cpha)
soft_spi_scl(dev, 0);
else
soft_spi_scl(dev, 1);
tmpdin <<= 1;
tmpdin |= dm_gpio_get_value(&plat->miso);
tmpdout <<= 1;
udelay(plat->spi_delay_us);
if (cpha)
soft_spi_scl(dev, 1);
}
/*
* If the number of bits isn't a multiple of 8, shift the last
* bits over to left-justify them. Then store the last byte
* read in.
*/
if (rxd) {
if ((bitlen % 8) != 0)
tmpdin <<= 8 - (bitlen % 8);
*rxd++ = tmpdin;
}
if (flags & SPI_XFER_END)
soft_spi_cs_deactivate(dev);
return 0;
}
static int soft_spi_set_speed(struct udevice *dev, unsigned int speed)
{
/* Accept any speed */
return 0;
}
static int soft_spi_set_mode(struct udevice *dev, unsigned int mode)
{
struct soft_spi_priv *priv = dev_get_priv(dev);
priv->mode = mode;
return 0;
}
static const struct dm_spi_ops soft_spi_ops = {
.claim_bus = soft_spi_claim_bus,
.release_bus = soft_spi_release_bus,
.xfer = soft_spi_xfer,
.set_speed = soft_spi_set_speed,
.set_mode = soft_spi_set_mode,
};
static int soft_spi_ofdata_to_platdata(struct udevice *dev)
{
struct soft_spi_platdata *plat = dev->platdata;
const void *blob = gd->fdt_blob;
int node = dev->of_offset;
plat->spi_delay_us = fdtdec_get_int(blob, node, "spi-delay-us", 0);
return 0;
}
static int soft_spi_probe(struct udevice *dev)
{
struct spi_slave *slave = dev_get_parentdata(dev);
struct soft_spi_platdata *plat = dev->platdata;
int cs_flags, clk_flags;
cs_flags = (slave->mode & SPI_CS_HIGH) ? 0 : GPIOD_ACTIVE_LOW;
clk_flags = (slave->mode & SPI_CPOL) ? GPIOD_ACTIVE_LOW : 0;
if (gpio_request_by_name(dev, "cs-gpio", 0, &plat->cs,
GPIOD_IS_OUT | cs_flags) ||
gpio_request_by_name(dev, "sclk-gpio", 0, &plat->sclk,
GPIOD_IS_OUT | clk_flags) ||
gpio_request_by_name(dev, "mosi-gpio", 0, &plat->mosi,
GPIOD_IS_OUT | GPIOD_IS_OUT_ACTIVE) ||
gpio_request_by_name(dev, "miso-gpio", 0, &plat->miso,
GPIOD_IS_IN))
return -EINVAL;
return 0;
}
static const struct udevice_id soft_spi_ids[] = {
{ .compatible = "u-boot,soft-spi" },
{ }
};
U_BOOT_DRIVER(soft_spi) = {
.name = "soft_spi",
.id = UCLASS_SPI,
.of_match = soft_spi_ids,
.ops = &soft_spi_ops,
.ofdata_to_platdata = soft_spi_ofdata_to_platdata,
.platdata_auto_alloc_size = sizeof(struct soft_spi_platdata),
.priv_auto_alloc_size = sizeof(struct soft_spi_priv),
.probe = soft_spi_probe,
};
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