Quelle  spi-xcomm.c   Sprache: C

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Analog Devices AD-FMCOMMS1-EBZ board I2C-SPI bridge driver
 *
 * Copyright 2012 Analog Devices Inc.
 * Author: Lars-Peter Clausen <lars@metafoo.de>
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/delay.h>
#include <linux/i2c.h>
#include <linux/gpio/driver.h>
#include <linux/spi/spi.h>
#include <linux/unaligned.h>

#define SPI_XCOMM_SETTINGS_LEN_OFFSET  10
#define SPI_XCOMM_SETTINGS_3WIRE  BIT(6)
#define SPI_XCOMM_SETTINGS_CS_HIGH  BIT(5)
#define SPI_XCOMM_SETTINGS_SAMPLE_END  BIT(4)
#define SPI_XCOMM_SETTINGS_CPHA   BIT(3)
#define SPI_XCOMM_SETTINGS_CPOL   BIT(2)
#define SPI_XCOMM_SETTINGS_CLOCK_DIV_MASK 0x3
#define SPI_XCOMM_SETTINGS_CLOCK_DIV_64  0x2
#define SPI_XCOMM_SETTINGS_CLOCK_DIV_16  0x1
#define SPI_XCOMM_SETTINGS_CLOCK_DIV_4  0x0

#define SPI_XCOMM_CMD_UPDATE_CONFIG 0x03
#define SPI_XCOMM_CMD_WRITE  0x04
#define SPI_XCOMM_CMD_GPIO_SET  0x05

#define SPI_XCOMM_CLOCK 48000000

struct spi_xcomm {
 struct i2c_client *i2c;

 struct gpio_chip gc;

 u16 settings;
 u16 chipselect;

 unsigned int current_speed;

 u8 buf[63];
};

static int spi_xcomm_gpio_set_value(struct gpio_chip *chip,
        unsigned int offset, int val)
{
 struct spi_xcomm *spi_xcomm = gpiochip_get_data(chip);
 unsigned char buf[2];

 buf[0] = SPI_XCOMM_CMD_GPIO_SET;
 buf[1] = !!val;

 return i2c_master_send(spi_xcomm->i2c, buf, 2);
}

static int spi_xcomm_gpio_get_direction(struct gpio_chip *chip,
     unsigned int offset)
{
 return GPIO_LINE_DIRECTION_OUT;
}

static int spi_xcomm_gpio_add(struct spi_xcomm *spi_xcomm)
{
 struct device *dev = &spi_xcomm->i2c->dev;

 if (!IS_ENABLED(CONFIG_GPIOLIB))
  return 0;

 spi_xcomm->gc.get_direction = spi_xcomm_gpio_get_direction;
 spi_xcomm->gc.set = spi_xcomm_gpio_set_value;
 spi_xcomm->gc.can_sleep = 1;
 spi_xcomm->gc.base = -1;
 spi_xcomm->gc.ngpio = 1;
 spi_xcomm->gc.label = spi_xcomm->i2c->name;
 spi_xcomm->gc.owner = THIS_MODULE;

 return devm_gpiochip_add_data(dev, &spi_xcomm->gc, spi_xcomm);
}

static int spi_xcomm_sync_config(struct spi_xcomm *spi_xcomm, unsigned int len)
{
 u16 settings;
 u8 *buf = spi_xcomm->buf;

 settings = spi_xcomm->settings;
 settings |= len << SPI_XCOMM_SETTINGS_LEN_OFFSET;

 buf[0] = SPI_XCOMM_CMD_UPDATE_CONFIG;
 put_unaligned_be16(settings, &buf[1]);
 put_unaligned_be16(spi_xcomm->chipselect, &buf[3]);

 return i2c_master_send(spi_xcomm->i2c, buf, 5);
}

static void spi_xcomm_chipselect(struct spi_xcomm *spi_xcomm,
     struct spi_device *spi, int is_active)
{
 unsigned long cs = spi_get_chipselect(spi, 0);
 u16 chipselect = spi_xcomm->chipselect;

 if (is_active)
  chipselect |= BIT(cs);
 else
  chipselect &= ~BIT(cs);

 spi_xcomm->chipselect = chipselect;
}

static int spi_xcomm_setup_transfer(struct spi_xcomm *spi_xcomm,
        struct spi_device *spi, struct spi_transfer *t,
        unsigned int *settings)
{
 if (t->len > 62)
  return -EINVAL;

 if (t->speed_hz != spi_xcomm->current_speed) {
  unsigned int divider;

  divider = DIV_ROUND_UP(SPI_XCOMM_CLOCK, t->speed_hz);
  if (divider >= 64)
   *settings |= SPI_XCOMM_SETTINGS_CLOCK_DIV_64;
  else if (divider >= 16)
   *settings |= SPI_XCOMM_SETTINGS_CLOCK_DIV_16;
  else
   *settings |= SPI_XCOMM_SETTINGS_CLOCK_DIV_4;

  spi_xcomm->current_speed = t->speed_hz;
 }

 if (spi->mode & SPI_CPOL)
  *settings |= SPI_XCOMM_SETTINGS_CPOL;
 else
  *settings &= ~SPI_XCOMM_SETTINGS_CPOL;

 if (spi->mode & SPI_CPHA)
  *settings &= ~SPI_XCOMM_SETTINGS_CPHA;
 else
  *settings |= SPI_XCOMM_SETTINGS_CPHA;

 if (spi->mode & SPI_3WIRE)
  *settings |= SPI_XCOMM_SETTINGS_3WIRE;
 else
  *settings &= ~SPI_XCOMM_SETTINGS_3WIRE;

 return 0;
}

static int spi_xcomm_txrx_bufs(struct spi_xcomm *spi_xcomm,
          struct spi_device *spi, struct spi_transfer *t)
{
 int ret;

 if (t->tx_buf) {
  spi_xcomm->buf[0] = SPI_XCOMM_CMD_WRITE;
  memcpy(spi_xcomm->buf + 1, t->tx_buf, t->len);

  ret = i2c_master_send(spi_xcomm->i2c, spi_xcomm->buf, t->len + 1);
  if (ret < 0)
   return ret;
  if (ret != t->len + 1)
   return -EIO;
 } else if (t->rx_buf) {
  ret = i2c_master_recv(spi_xcomm->i2c, t->rx_buf, t->len);
  if (ret < 0)
   return ret;
  if (ret != t->len)
   return -EIO;
 }

 return t->len;
}

static int spi_xcomm_transfer_one(struct spi_controller *host,
      struct spi_message *msg)
{
 struct spi_xcomm *spi_xcomm = spi_controller_get_devdata(host);
 unsigned int settings = spi_xcomm->settings;
 struct spi_device *spi = msg->spi;
 unsigned int cs_change = 0;
 struct spi_transfer *t;
 bool is_first = true;
 int status = 0;
 bool is_last;

 spi_xcomm_chipselect(spi_xcomm, spi, true);

 list_for_each_entry(t, &msg->transfers, transfer_list) {
  if (!t->tx_buf && !t->rx_buf && t->len) {
   status = -EINVAL;
   break;
  }

  status = spi_xcomm_setup_transfer(spi_xcomm, spi, t, &settings);
  if (status < 0)
   break;

  is_last = list_is_last(&t->transfer_list, &msg->transfers);
  cs_change = t->cs_change;

  if (cs_change ^ is_last)
   settings |= BIT(5);
  else
   settings &= ~BIT(5);

  if (t->rx_buf) {
   spi_xcomm->settings = settings;
   status = spi_xcomm_sync_config(spi_xcomm, t->len);
   if (status < 0)
    break;
  } else if (settings != spi_xcomm->settings || is_first) {
   spi_xcomm->settings = settings;
   status = spi_xcomm_sync_config(spi_xcomm, 0);
   if (status < 0)
    break;
  }

  if (t->len) {
   status = spi_xcomm_txrx_bufs(spi_xcomm, spi, t);

   if (status < 0)
    break;

   if (status > 0)
    msg->actual_length += status;
  }
  status = 0;

  spi_transfer_delay_exec(t);

  is_first = false;
 }

 if (status != 0 || !cs_change)
  spi_xcomm_chipselect(spi_xcomm, spi, false);

 msg->status = status;
 spi_finalize_current_message(host);

 return status;
}

static int spi_xcomm_probe(struct i2c_client *i2c)
{
 struct spi_xcomm *spi_xcomm;
 struct spi_controller *host;
 int ret;

 host = devm_spi_alloc_host(&i2c->dev, sizeof(*spi_xcomm));
 if (!host)
  return -ENOMEM;

 spi_xcomm = spi_controller_get_devdata(host);
 spi_xcomm->i2c = i2c;

 host->num_chipselect = 16;
 host->mode_bits = SPI_CPHA | SPI_CPOL | SPI_3WIRE;
 host->bits_per_word_mask = SPI_BPW_MASK(8);
 host->flags = SPI_CONTROLLER_HALF_DUPLEX;
 host->transfer_one_message = spi_xcomm_transfer_one;
 host->dev.of_node = i2c->dev.of_node;

 ret = devm_spi_register_controller(&i2c->dev, host);
 if (ret < 0)
  return ret;

 return spi_xcomm_gpio_add(spi_xcomm);
}

static const struct i2c_device_id spi_xcomm_ids[] = {
 { "spi-xcomm" },
 { },
};
MODULE_DEVICE_TABLE(i2c, spi_xcomm_ids);

static struct i2c_driver spi_xcomm_driver = {
 .driver = {
  .name = "spi-xcomm",
 },
 .id_table = spi_xcomm_ids,
 .probe  = spi_xcomm_probe,
};
module_i2c_driver(spi_xcomm_driver);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Lars-Peter Clausen ");
MODULE_DESCRIPTION("Analog Devices AD-FMCOMMS1-EBZ board I2C-SPI bridge driver");