/*
 * Copyright (C) 2012-2013 Uwe Kleine-Koenig for Pengutronix
 *
 * This program is free software; you can redistribute it and/or modify it under
 * the terms of the GNU General Public License version 2 as published by the
 * Free Software Foundation.
 */
#include <linux/kernel.h>
#include <linux/io.h>
#include <linux/spi/spi.h>
#include <linux/spi/spi_bitbang.h>
#include <linux/gpio.h>
#include <linux/interrupt.h>
#include <linux/platform_device.h>
#include <linux/clk.h>
#include <linux/err.h>
#include <linux/module.h>
#include <linux/of_gpio.h>
#include <linux/platform_data/efm32-spi.h>

#define DRIVER_NAME "efm32-spi"

#define MASK_VAL(mask, val)		((val << __ffs(mask)) & mask)

#define REG_CTRL		0x00
#define REG_CTRL_SYNC			0x0001
#define REG_CTRL_CLKPOL			0x0100
#define REG_CTRL_CLKPHA			0x0200
#define REG_CTRL_MSBF			0x0400
#define REG_CTRL_TXBIL			0x1000

#define REG_FRAME		0x04
#define REG_FRAME_DATABITS__MASK	0x000f
#define REG_FRAME_DATABITS(n)		((n) - 3)

#define REG_CMD			0x0c
#define REG_CMD_RXEN			0x0001
#define REG_CMD_RXDIS			0x0002
#define REG_CMD_TXEN			0x0004
#define REG_CMD_TXDIS			0x0008
#define REG_CMD_MASTEREN		0x0010

#define REG_STATUS		0x10
#define REG_STATUS_TXENS		0x0002
#define REG_STATUS_TXC			0x0020
#define REG_STATUS_TXBL			0x0040
#define REG_STATUS_RXDATAV		0x0080

#define REG_CLKDIV		0x14

#define REG_RXDATAX		0x18
#define REG_RXDATAX_RXDATA__MASK	0x01ff
#define REG_RXDATAX_PERR		0x4000
#define REG_RXDATAX_FERR		0x8000

#define REG_TXDATA		0x34

#define REG_IF		0x40
#define REG_IF_TXBL			0x0002
#define REG_IF_RXDATAV			0x0004

#define REG_IFS		0x44
#define REG_IFC		0x48
#define REG_IEN		0x4c

#define REG_ROUTE		0x54
#define REG_ROUTE_RXPEN			0x0001
#define REG_ROUTE_TXPEN			0x0002
#define REG_ROUTE_CLKPEN		0x0008
#define REG_ROUTE_LOCATION__MASK	0x0700
#define REG_ROUTE_LOCATION(n)		MASK_VAL(REG_ROUTE_LOCATION__MASK, (n))

struct efm32_spi_ddata {
	struct spi_bitbang bitbang;

	spinlock_t lock;

	struct clk *clk;
	void __iomem *base;
	unsigned int rxirq, txirq;
	struct efm32_spi_pdata pdata;

	/* irq data */
	struct completion done;
	const u8 *tx_buf;
	u8 *rx_buf;
	unsigned tx_len, rx_len;

	/* chip selects */
	unsigned csgpio[];
};

#define ddata_to_dev(ddata)	(&(ddata->bitbang.master->dev))
#define efm32_spi_vdbg(ddata, format, arg...)	\
	dev_vdbg(ddata_to_dev(ddata), format, ##arg)

static void efm32_spi_write32(struct efm32_spi_ddata *ddata,
		u32 value, unsigned offset)
{
	writel_relaxed(value, ddata->base + offset);
}

static u32 efm32_spi_read32(struct efm32_spi_ddata *ddata, unsigned offset)
{
	return readl_relaxed(ddata->base + offset);
}

static void efm32_spi_chipselect(struct spi_device *spi, int is_on)
{
	struct efm32_spi_ddata *ddata = spi_master_get_devdata(spi->master);
	int value = !(spi->mode & SPI_CS_HIGH) == !(is_on == BITBANG_CS_ACTIVE);

	gpio_set_value(ddata->csgpio[spi->chip_select], value);
}

static int efm32_spi_setup_transfer(struct spi_device *spi,
		struct spi_transfer *t)
{
	struct efm32_spi_ddata *ddata = spi_master_get_devdata(spi->master);

	unsigned bpw = t->bits_per_word ?: spi->bits_per_word;
	unsigned speed = t->speed_hz ?: spi->max_speed_hz;
	unsigned long clkfreq = clk_get_rate(ddata->clk);
	u32 clkdiv;

	efm32_spi_write32(ddata, REG_CTRL_SYNC | REG_CTRL_MSBF |
			(spi->mode & SPI_CPHA ? REG_CTRL_CLKPHA : 0) |
			(spi->mode & SPI_CPOL ? REG_CTRL_CLKPOL : 0), REG_CTRL);

	efm32_spi_write32(ddata,
			REG_FRAME_DATABITS(bpw), REG_FRAME);

	if (2 * speed >= clkfreq)
		clkdiv = 0;
	else
		clkdiv = 64 * (DIV_ROUND_UP(2 * clkfreq, speed) - 4);

	if (clkdiv > (1U << 21))
		return -EINVAL;

	efm32_spi_write32(ddata, clkdiv, REG_CLKDIV);
	efm32_spi_write32(ddata, REG_CMD_MASTEREN, REG_CMD);
	efm32_spi_write32(ddata, REG_CMD_RXEN | REG_CMD_TXEN, REG_CMD);

	return 0;
}

static void efm32_spi_tx_u8(struct efm32_spi_ddata *ddata)
{
	u8 val = 0;

	if (ddata->tx_buf) {
		val = *ddata->tx_buf;
		ddata->tx_buf++;
	}

	ddata->tx_len--;
	efm32_<style>
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