linux-imx

/*

 * NXP SC18IS602/603 SPI driver

 *

 * Copyright (C) Guenter Roeck <linux@roeck-us.net>

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 2 of the License, or

 * (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 */

​

#include <linux/kernel.h>

#include <linux/err.h>

#include <linux/module.h>

#include <linux/spi/spi.h>

#include <linux/i2c.h>

#include <linux/delay.h>

#include <linux/pm_runtime.h>

#include <linux/of_device.h>

#include <linux/of.h>

#include <linux/platform_data/sc18is602.h>

#include <linux/gpio/consumer.h>

​

enum chips { sc18is602, sc18is602b, sc18is603 };

​

#define SC18IS602_BUFSIZ        200

#define SC18IS602_CLOCK         7372000

​

#define SC18IS602_MODE_CPHA     BIT(2)

#define SC18IS602_MODE_CPOL     BIT(3)

#define SC18IS602_MODE_LSB_FIRST    BIT(5)

#define SC18IS602_MODE_CLOCK_DIV_4  0x0

#define SC18IS602_MODE_CLOCK_DIV_16 0x1

#define SC18IS602_MODE_CLOCK_DIV_64 0x2

#define SC18IS602_MODE_CLOCK_DIV_128    0x3

​

struct sc18is602 {

    struct spi_master   *master;

    struct device       *dev;

    u8          ctrl;

    u32         freq;

    u32         speed;

​

    /* I2C data */

    struct i2c_client   *client;

    enum chips      id;

    u8          buffer[SC18IS602_BUFSIZ + 1];

    int         tlen;   /* Data queued for tx in buffer */

    int         rindex; /* Receive data index in buffer */

​

    struct gpio_desc    *reset;

};

​

static int sc18is602_wait_ready(struct sc18is602 *hw, int len)

{

    int i, err;

    int usecs = 1000000 * len / hw->speed + 1;

    u8 dummy[1];

​

    for (i = 0; i < 10; i++) {

        err = i2c_master_recv(hw->client, dummy, 1);

        if (err >= 0)

            return 0;

        usleep_range(usecs, usecs * 2);

    }

    return -ETIMEDOUT;

}

​

static int sc18is602_txrx(struct sc18is602 *hw, struct spi_message *msg,

              struct spi_transfer *t, bool do_transfer)

{

    unsigned int len = t->len;

    int ret;

​

    if (hw->tlen == 0) {

        /* First byte (I2C command) is chip select */

        hw->buffer[0] = 1 << msg->spi->chip_select;

        hw->tlen = 1;

        hw->rindex = 0;

    }

    /*

     * We can not immediately send data to the chip, since each I2C message

     * resembles a full SPI message (from CS active to CS inactive).

     * Enqueue messages up to the first read or until do_transfer is true.

     */

    if (t->tx_buf) {

        memcpy(&hw->buffer[hw->tlen], t->tx_buf, len);