path: root/target/linux/lantiq/patches-4.1/0033-SPI-MIPS-lantiq-adds-spi-xway.patch

From e75df4f96373e5d16f8ca13aa031e54cdcfeda62 Mon Sep 17 00:00:00 2001
From: John Crispin <blogic@openwrt.org>
Date: Wed, 13 Mar 2013 09:29:37 +0100
Subject: [PATCH 33/36] SPI: MIPS: lantiq: adds spi-xway

This patch adds support for the SPI core found on several Lantiq SoCs.
The Driver has been runtime tested in combination with m25p80 Flash Devices
on Amazon_SE and VR9.

Signed-off-by: Daniel Schwierzeck <daniel.schwierzeck@googlemail.com>
Signed-off-by: John Crispin <blogic@openwrt.org>
---
 drivers/spi/Kconfig    |    8 +
 drivers/spi/Makefile   |    1 +
 drivers/spi/spi-xway.c |  977 ++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 986 insertions(+)
 create mode 100644 drivers/spi/spi-xway.c

--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -626,6 +626,14 @@ config SPI_NUC900
 	help
 	  SPI driver for Nuvoton NUC900 series ARM SoCs
 
+config SPI_XWAY
+	tristate "Lantiq SPI controller"
+	depends on LANTIQ
+	select SPI_BITBANG
+	help
+	  This driver supports the Lantiq SoC SPI controller in master
+	  mode.
+
 #
 # Add new SPI master controllers in alphabetical order above this line
 #
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -90,3 +90,4 @@ obj-$(CONFIG_SPI_TXX9)			+= spi-txx9.o
 obj-$(CONFIG_SPI_XCOMM)		+= spi-xcomm.o
 obj-$(CONFIG_SPI_XILINX)		+= spi-xilinx.o
 obj-$(CONFIG_SPI_XTENSA_XTFPGA)		+= spi-xtensa-xtfpga.o
+obj-$(CONFIG_SPI_XWAY)			+= spi-xway.o
--- /dev/null
+++ b/drivers/spi/spi-xway.c
@@ -0,0 +1,991 @@
+/*
+ * Lantiq SoC SPI controller
+ *
+ * Copyright (C) 2011 Daniel Schwierzeck <daniel.schwierzeck@googlemail.com>
+ * Copyright (C) 2012 John Crispin <blogic@openwrt.org>
+ *
+ * This program is free software; you can distribute 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/init.h>
+#include <linux/module.h>
+#include <linux/workqueue.h>
+#include <linux/platform_device.h>
+#include <linux/io.h>
+#include <linux/sched.h>
+#include <linux/delay.h>
+#include <linux/interrupt.h>
+#include <linux/completion.h>
+#include <linux/spinlock.h>
+#include <linux/err.h>
+#include <linux/clk.h>
+#include <linux/spi/spi.h>
+#include <linux/spi/spi_bitbang.h>
+#include <linux/of_irq.h>
+
+#include <lantiq_soc.h>
+
+#define LTQ_SPI_CLC		0x00	/* Clock control */
+#define LTQ_SPI_PISEL		0x04	/* Port input select */
+#define LTQ_SPI_ID		0x08	/* Identification */
+#define LTQ_SPI_CON		0x10	/* Control */
+#define LTQ_SPI_STAT		0x14	/* Status */
+#define LTQ_SPI_WHBSTATE	0x18	/* Write HW modified state */
+#define LTQ_SPI_TB		0x20	/* Transmit buffer */
+#define LTQ_SPI_RB		0x24	/* Receive buffer */
+#define LTQ_SPI_RXFCON		0x30	/* Receive FIFO control */
+#define LTQ_SPI_TXFCON		0x34	/* Transmit FIFO control */
+#define LTQ_SPI_FSTAT		0x38	/* FIFO status */
+#define LTQ_SPI_BRT		0x40	/* Baudrate timer */
+#define LTQ_SPI_BRSTAT		0x44	/* Baudrate timer status */
+#define LTQ_SPI_SFCON		0x60	/* Serial frame control */
+#define LTQ_SPI_SFSTAT		0x64	/* Serial frame status */
+#define LTQ_SPI_GPOCON		0x70	/* General purpose output control */
+#define LTQ_SPI_GPOSTAT		0x74	/* General purpose output status */
+#define LTQ_SPI_FGPO		0x78	/* Forced general purpose output */
+#define LTQ_SPI_RXREQ		0x80	/* Receive request */
+#define LTQ_SPI_RXCNT		0x84	/* Receive count */
+#define LTQ_SPI_DMACON		0xEC	/* DMA control */
+#define LTQ_SPI_IRNEN		0xF4	/* Interrupt node enable */
+#define LTQ_SPI_IRNICR		0xF8	/* Interrupt node interrupt capture */
+#define LTQ_SPI_IRNCR		0xFC	/* Interrupt node control */
+
+#define LTQ_SPI_CLC_SMC_SHIFT	16	/* Clock divider for sleep mode */
+#define LTQ_SPI_CLC_SMC_MASK	0xFF
+#define LTQ_SPI_CLC_RMC_SHIFT	8	/* Clock divider for normal run mode */
+#define LTQ_SPI_CLC_RMC_MASK	0xFF
+#define LTQ_SPI_CLC_DISS	BIT(1)	/* Disable status bit */
+#define LTQ_SPI_CLC_DISR	BIT(0)	/* Disable request bit */
+
+#define LTQ_SPI_ID_TXFS_SHIFT	24	/* Implemented TX FIFO size */
+#define LTQ_SPI_ID_TXFS_MASK	0x3F
+#define LTQ_SPI_ID_RXFS_SHIFT	16	/* Implemented RX FIFO size */
+#define LTQ_SPI_ID_RXFS_MASK	0x3F
+#define LTQ_SPI_ID_REV_MASK	0x1F	/* Hardware revision number */
+#define LTQ_SPI_ID_CFG		BIT(5)	/* DMA interface support */
+
+#define LTQ_SPI_CON_BM_SHIFT	16	/* Data width selection */
+#define LTQ_SPI_CON_BM_MASK	0x1F
+#define LTQ_SPI_CON_EM		BIT(24)	/* Echo mode */
+#define LTQ_SPI_CON_IDLE	BIT(23)	/* Idle bit value */
+#define LTQ_SPI_CON_ENBV	BIT(22)	/* Enable byte valid control */
+#define LTQ_SPI_CON_RUEN	BIT(12)	/* Receive underflow error enable */
+#define LTQ_SPI_CON_TUEN	BIT(11)	/* Transmit underflow error enable */
+#define LTQ_SPI_CON_AEN		BIT(10)	/* Abort error enable */
+#define LTQ_SPI_CON_REN		BIT(9)	/* Receive overflow error enable */
+#define LTQ_SPI_CON_TEN		BIT(8)	/* Transmit overflow error enable */
+#define LTQ_SPI_CON_LB		BIT(7)	/* Loopback control */
+#define LTQ_SPI_CON_PO		BIT(6)	/* Clock polarity control */
+#define LTQ_SPI_CON_PH		BIT(5)	/* Clock phase control */
+#define LTQ_SPI_CON_HB		BIT(4)	/* Heading control */
+#define LTQ_SPI_CON_RXOFF	BIT(1)	/* Switch receiver off */
+#define LTQ_SPI_CON_TXOFF	BIT(0)	/* Switch transmitter off */
+
+#define LTQ_SPI_STAT_RXBV_MASK	0x7
+#define LTQ_SPI_STAT_RXBV_SHIFT	28
+#define LTQ_SPI_STAT_BSY	BIT(13)	/* Busy flag */
+#define LTQ_SPI_STAT_RUE	BIT(12)	/* Receive underflow error flag */
+#define LTQ_SPI_STAT_TUE	BIT(11)	/* Transmit underflow error flag */
+#define LTQ_SPI_STAT_AE		BIT(10)	/* Abort error flag */
+#define LTQ_SPI_STAT_RE		BIT(9)	/* Receive error flag */
+#define LTQ_SPI_STAT_TE		BIT(8)	/* Transmit error flag */
+#define LTQ_SPI_STAT_MS		BIT(1)	/* Master/slave select bit */
+#define LTQ_SPI_STAT_EN		BIT(0)	/* Enable bit */
+
+#define LTQ_SPI_WHBSTATE_SETTUE	BIT(15)	/* Set transmit underflow error flag */
+#define LTQ_SPI_WHBSTATE_SETAE	BIT(14)	/* Set abort error flag */
+#define LTQ_SPI_WHBSTATE_SETRE	BIT(13)	/* Set receive error flag */
+#define LTQ_SPI_WHBSTATE_SETTE	BIT(12)	/* Set transmit error flag */
+#define LTQ_SPI_WHBSTATE_CLRTUE	BIT(11)	/* Clear transmit underflow error
+						flag */
+#define LTQ_SPI_WHBSTATE_CLRAE	BIT(10)	/* Clear abort error flag */
+#define LTQ_SPI_WHBSTATE_CLRRE	BIT(9)	/* Clear receive error flag */
+#define LTQ_SPI_WHBSTATE_CLRTE	BIT(8)	/* Clear transmit error flag */
+#define LTQ_SPI_WHBSTATE_SETME	BIT(7)	/* Set mode error flag */
+#define LTQ_SPI_WHBSTATE_CLRME	BIT(6)	/* Clear mode error flag */
+#define LTQ_SPI_WHBSTATE_SETRUE	BIT(5)	/* Set receive underflow error flag */
+#define LTQ_SPI_WHBSTATE_CLRRUE	BIT(4)	/* Clear receive underflow error flag */
+#define LTQ_SPI_WHBSTATE_SETMS	BIT(3)	/* Set master select bit */
+#define LTQ_SPI_WHBSTATE_CLRMS	BIT(2)	/* Clear master select bit */
+#define LTQ_SPI_WHBSTATE_SETEN	BIT(1)	/* Set enable bit (operational mode) */
+#define LTQ_SPI_WHBSTATE_CLREN	BIT(0)	/* Clear enable bit (config mode */
+#define LTQ_SPI_WHBSTATE_CLR_ERRORS	0x0F50
+
+#define LTQ_SPI_RXFCON_RXFITL_SHIFT	8 /* FIFO interrupt trigger level */
+#define LTQ_SPI_RXFCON_RXFITL_MASK	0x3F
+#define LTQ_SPI_RXFCON_RXFLU		BIT(1)	/* FIFO flush */
+#define LTQ_SPI_RXFCON_RXFEN		BIT(0)	/* FIFO enable */
+
+#define LTQ_SPI_TXFCON_TXFITL_SHIFT	8 /* FIFO interrupt trigger level */
+#define LTQ_SPI_TXFCON_TXFITL_MASK	0x3F
+#define LTQ_SPI_TXFCON_TXFLU		BIT(1)	/* FIFO flush */
+#define LTQ_SPI_TXFCON_TXFEN		BIT(0)	/* FIFO enable */
+
+#define LTQ_SPI_FSTAT_RXFFL_MASK	0x3f
+#define LTQ_SPI_FSTAT_RXFFL_SHIFT	0
+#define LTQ_SPI_FSTAT_TXFFL_MASK	0x3f
+#define LTQ_SPI_FSTAT_TXFFL_SHIFT	8
+
+#define LTQ_SPI_GPOCON_ISCSBN_SHIFT	8
+#define LTQ_SPI_GPOCON_INVOUTN_SHIFT	0
+
+#define LTQ_SPI_FGPO_SETOUTN_SHIFT	8
+#define LTQ_SPI_FGPO_CLROUTN_SHIFT	0
+
+#define LTQ_SPI_RXREQ_RXCNT_MASK	0xFFFF	/* Receive count value */
+#define LTQ_SPI_RXCNT_TODO_MASK		0xFFFF	/* Recevie to-do value */
+
+#define LTQ_SPI_IRNEN_F		BIT(3)	/* Frame end interrupt request */
+#define LTQ_SPI_IRNEN_E		BIT(2)	/* Error end interrupt request */
+#define LTQ_SPI_IRNEN_T		BIT(0)  /* Transmit end interrupt request */
+#define LTQ_SPI_IRNEN_R		BIT(1)  /* Receive end interrupt request */
+#define LTQ_SPI_IRNEN_T_XWAY	BIT(1)  /* Transmit end interrupt request */
+#define LTQ_SPI_IRNEN_R_XWAY	BIT(0)  /* Receive end interrupt request */
+#define LTQ_SPI_IRNEN_ALL	0xF
+
+struct ltq_spi {
+	struct spi_bitbang	bitbang;
+	struct completion	done;
+	spinlock_t		lock;
+
+	struct device		*dev;
+	void __iomem		*base;
+	struct clk		*fpiclk;
+	struct clk		*spiclk;
+
+	int			status;
+	int			irq[3];
+
+	const u8		*tx;
+	u8			*rx;
+	u32			tx_cnt;
+	u32			rx_cnt;
+	u32			len;
+	struct spi_transfer	*curr_transfer;
+
+	u32 (*get_tx) (struct ltq_spi *);
+
+	u16			txfs;
+	u16			rxfs;
+	unsigned		dma_support:1;
+	unsigned		cfg_mode:1;
+
+	u32			irnen_t;
+	u32			irnen_r;
+};
+
+static inline struct ltq_spi *ltq_spi_to_hw(struct spi_device *spi)
+{
+	return spi_master_get_devdata(spi->master);
+}
+
+static inline u32 ltq_spi_reg_read(struct ltq_spi *hw, u32 reg)
+{
+	return ioread32be(hw->base + reg);
+}
+
+static inline void ltq_spi_reg_write(struct ltq_spi *hw, u32 val, u32 reg)
+{
+	iowrite32be(val, hw->base + reg);
+}
+
+static inline void ltq_spi_reg_setbit(struct ltq_spi *hw, u32 bits, u32 reg)
+{
+	u32 val;
+
+	val = ltq_spi_reg_read(hw, reg);
+	val |= bits;
+	ltq_spi_reg_write(hw, val, reg);
+}
+
+static inline void ltq_spi_reg_clearbit(struct ltq_spi *hw, u32 bits, u32 reg)
+{
+	u32 val;
+
+	val = ltq_spi_reg_read(hw, reg);
+	val &= ~bits;
+	ltq_spi_reg_write(hw, val, reg);
+}
+
+static void ltq_spi_hw_enable(struct ltq_spi *hw)
+{
+	u32 clc;
+
+	/* Power-up module */
+	clk_enable(hw->spiclk);
+
+	/*
+	 * Set clock divider for run mode to 1 to
+	 * run at same frequency as FPI bus
+	 */
+	clc = (1 << LTQ_SPI_CLC_RMC_SHIFT);
+	ltq_spi_reg_write(hw, clc, LTQ_SPI_CLC);
+}
+
+static void ltq_spi_hw_disable(struct ltq_spi *hw)
+{
+	/* Set clock divider to 0 and set module disable bit */
+	ltq_spi_reg_write(hw, LTQ_SPI_CLC_DISS, LTQ_SPI_CLC);
+
+	/* Power-down module */
+	clk_disable(hw->spiclk);
+}
+
+static void ltq_spi_reset_fifos(struct ltq_spi *hw)
+{
+	u32 val;
+
+	/*
+	 * Enable and flush FIFOs. Set interrupt trigger level to
+	 * half of FIFO count implemented in hardware.
+	 */
+	if (hw->txfs > 1) {
+		val = hw->txfs << (LTQ_SPI_TXFCON_TXFITL_SHIFT - 1);
+		val |= LTQ_SPI_TXFCON_TXFEN | LTQ_SPI_TXFCON_TXFLU;
+		ltq_spi_reg_write(hw, val, LTQ_SPI_TXFCON);
+	}
+
+	if (hw->rxfs > 1) {
+		val = hw->rxfs << (LTQ_SPI_RXFCON_RXFITL_SHIFT - 1);
+		val |= LTQ_SPI_RXFCON_RXFEN | LTQ_SPI_RXFCON_RXFLU;
+		ltq_spi_reg_write(hw, val, LTQ_SPI_RXFCON);
+	}
+}
+
+static inline int ltq_spi_wait_ready(struct ltq_spi *hw)
+{
+	u32 stat;
+	unsigned long timeout;
+
+	timeout = jiffies + msecs_to_jiffies(200);
+
+	do {
+		stat = ltq_spi_reg_read(hw, LTQ_SPI_STAT);
+		if (!(stat & LTQ_SPI_STAT_BSY))
+			return 0;
+
+		cond_resched();
+	} while (!time_after_eq(jiffies, timeout));
+
+	dev_err(hw->dev, "SPI wait ready timed out stat: %x\n", stat);
+
+	return -ETIMEDOUT;
+}
+
+static void ltq_spi_config_mode_set(struct ltq_spi *hw)
+{
+	if (hw->cfg_mode)
+		return;
+
+	/*
+	 * Putting the SPI module in config mode is only safe if no
+	 * transfer is in progress as indicated by busy flag STATE.BSY.
+	 */
+	if (ltq_spi_wait_ready(hw)) {
+		ltq_spi_reset_fifos(hw);
+		hw->status = -ETIMEDOUT;
+	}
+	ltq_spi_reg_write(hw, LTQ_SPI_WHBSTATE_CLREN, LTQ_SPI_WHBSTATE);
+
+	hw->cfg_mode = 1;
+}
+
+static void ltq_spi_run_mode_set(struct ltq_spi *hw)
+{
+	if (!hw->cfg_mode)
+		return;
+
+	ltq_spi_reg_write(hw, LTQ_SPI_WHBSTATE_SETEN, LTQ_SPI_WHBSTATE);
+
+	hw->cfg_mode = 0;
+}
+
+static u32 ltq_spi_tx_word_u8(struct ltq_spi *hw)
+{
+	const u8 *tx = hw->tx;
+	u32 data = *tx++;
+
+	hw->tx_cnt++;
+	hw->tx++;
+
+	return data;
+}
+
+static u32 ltq_spi_tx_word_u16(struct ltq_spi *hw)
+{
+	const u16 *tx = (u16 *) hw->tx;
+	u32 data = *tx++;
+
+	hw->tx_cnt += 2;
+	hw->tx += 2;
+
+	return data;
+}
+
+static u32 ltq_spi_tx_word_u32(struct ltq_spi *hw)
+{
+	const u32 *tx = (u32 *) hw->tx;
+	u32 data = *tx++;
+
+	hw->tx_cnt += 4;
+	hw->tx += 4;
+
+	return data;
+}
+
+static void ltq_spi_bits_per_word_set(struct spi_device *spi)
+{
+	struct ltq_spi *hw = ltq_spi_to_hw(spi);
+	u32 bm;
+	u8 bits_per_word = spi->bits_per_word;
+
+	/*
+	 * Use either default value of SPI device or value
+	 * from current transfer.
+	 */
+	if (hw->curr_transfer && hw->curr_transfer->bits_per_word)
+		bits_per_word = hw->curr_transfer->bits_per_word;
+
+	if (bits_per_word <= 8)
+		hw->get_tx = ltq_spi_tx_word_u8;
+	else if (bits_per_word <= 16)
+		hw->get_tx = ltq_spi_tx_word_u16;
+	else if (bits_per_word <= 32)
+		hw->get_tx = ltq_spi_tx_word_u32;
+
+	/* CON.BM value = bits_per_word - 1 */
+	bm = (bits_per_word - 1) << LTQ_SPI_CON_BM_SHIFT;
+
+	ltq_spi_reg_clearbit(hw, LTQ_SPI_CON_BM_MASK <<
+			     LTQ_SPI_CON_BM_SHIFT, LTQ_SPI_CON);
+	ltq_spi_reg_setbit(hw, bm, LTQ_SPI_CON);
+}
+
+static void ltq_spi_speed_set(struct spi_device *spi)
+{
+	struct ltq_spi *hw = ltq_spi_to_hw(spi);
+	u32 br, max_speed_hz, spi_clk;
+	u32 speed_hz = spi->max_speed_hz;
+
+	/*
+	 * Use either default value of SPI device or value
+	 * from current transfer.
+	 */
+	if (hw->curr_transfer && hw->curr_transfer->speed_hz)
+		speed_hz = hw->curr_transfer->speed_hz;
+
+	/*
+	 * SPI module clock is derived from FPI bus clock dependent on
+	 * divider value in CLC.RMS which is always set to 1.
+	 */
+	spi_clk = clk_get_rate(hw->fpiclk);
+
+	/*
+	 * Maximum SPI clock frequency in master mode is half of
+	 * SPI module clock frequency. Maximum reload value of
+	 * baudrate generator BR is 2^16.
+	 */
+	max_speed_hz = spi_clk / 2;
+	if (speed_hz >= max_speed_hz)
+		br = 0;
+	else
+		br = (max_speed_hz / speed_hz) - 1;
+
+	if (br > 0xFFFF)
+		br = 0xFFFF;
+
+	ltq_spi_reg_write(hw, br, LTQ_SPI_BRT);
+}
+
+static void ltq_spi_clockmode_set(struct spi_device *spi)
+{
+	struct ltq_spi *hw = ltq_spi_to_hw(spi);
+	u32 con;
+
+	con = ltq_spi_reg_read(hw, LTQ_SPI_CON);
+
+	/*
+	 * SPI mode mapping in CON register:
+	 * Mode CPOL CPHA CON.PO CON.PH
+	 *  0    0    0      0      1
+	 *  1    0    1      0      0
+	 *  2    1    0      1      1
+	 *  3    1    1      1      0
+	 */
+	if (spi->mode & SPI_CPHA)
+		con &= ~LTQ_SPI_CON_PH;
+	else
+		con |= LTQ_SPI_CON_PH;
+
+	if (spi->mode & SPI_CPOL)
+		con |= LTQ_SPI_CON_PO;
+	else
+		con &= ~LTQ_SPI_CON_PO;
+
+	/* Set heading control */
+	if (spi->mode & SPI_LSB_FIRST)
+		con &= ~LTQ_SPI_CON_HB;
+	else
+		con |= LTQ_SPI_CON_HB;
+
+	ltq_spi_reg_write(hw, con, LTQ_SPI_CON);
+}
+
+static void ltq_spi_xmit_set(struct ltq_spi *hw, struct spi_transfer *t)
+{
+	u32 con;
+
+	con = ltq_spi_reg_read(hw, LTQ_SPI_CON);
+
+	if (t) {
+		if (t->tx_buf && t->rx_buf) {
+			con &= ~(LTQ_SPI_CON_TXOFF | LTQ_SPI_CON_RXOFF);
+		} else if (t->rx_buf) {
+			con &= ~LTQ_SPI_CON_RXOFF;
+			con |= LTQ_SPI_CON_TXOFF;
+		} else if (t->tx_buf) {
+			con &= ~LTQ_SPI_CON_TXOFF;
+			con |= LTQ_SPI_CON_RXOFF;
+		}
+	} else
+		con |= (LTQ_SPI_CON_TXOFF | LTQ_SPI_CON_RXOFF);
+
+	ltq_spi_reg_write(hw, con, LTQ_SPI_CON);
+}
+
+static void ltq_spi_internal_cs_activate(struct spi_device *spi)
+{
+	struct ltq_spi *hw = ltq_spi_to_hw(spi);
+	u32 fgpo;
+
+	fgpo = (1 << (spi->chip_select + LTQ_SPI_FGPO_CLROUTN_SHIFT));
+	ltq_spi_reg_setbit(hw, fgpo, LTQ_SPI_FGPO);
+}
+
+static void ltq_spi_internal_cs_deactivate(struct spi_device *spi)
+{
+	struct ltq_spi *hw = ltq_spi_to_hw(spi);
+	u32 fgpo;
+
+	fgpo = (1 << (spi->chip_select + LTQ_SPI_FGPO_SETOUTN_SHIFT));
+	ltq_spi_reg_setbit(hw, fgpo, LTQ_SPI_FGPO);
+}
+
+static void ltq_spi_chipselect(struct spi_device *spi, int cs)
+{
+	struct ltq_spi *hw = ltq_spi_to_hw(spi);
+
+	if (ltq_spi_wait_ready(hw))
+		dev_err(&spi->dev, "wait failed\n");
+
+	switch (cs) {
+	case BITBANG_CS_ACTIVE:
+		ltq_spi_bits_per_word_set(spi);
+		ltq_spi_speed_set(spi);
+		ltq_spi_clockmode_set(spi);
+		ltq_spi_run_mode_set(hw);
+		ltq_spi_internal_cs_activate(spi);
+		break;
+
+	case BITBANG_CS_INACTIVE:
+		ltq_spi_internal_cs_deactivate(spi);
+		ltq_spi_config_mode_set(hw);
+		break;
+	}
+}
+
+static int ltq_spi_setup_transfer(struct spi_device *spi,
+				  struct spi_transfer *t)
+{
+	struct ltq_spi *hw = ltq_spi_to_hw(spi);
+	u8 bits_per_word = spi->bits_per_word;
+
+	hw->curr_transfer = t;
+
+	if (t && t->bits_per_word)
+		bits_per_word = t->bits_per_word;
+
+	if (bits_per_word > 32)
+		return -EINVAL;
+
+	return 0;
+}
+
+static int ltq_spi_setup(struct spi_device *spi)
+{
+	struct ltq_spi *hw = ltq_spi_to_hw(spi);
+	u32 gpocon, fgpo;
+
+	/* Set default word length to 8 if not set */
+	if (!spi->bits_per_word)
+		spi->bits_per_word = 8;
+
+	if (spi->bits_per_word > 32)
+		return -EINVAL;
+
+	/*
+	 * Up to six GPIOs can be connected to the SPI module
+	 * via GPIO alternate function to control the chip select lines.
+	 */
+	gpocon = (1 << (spi->chip_select +
+			LTQ_SPI_GPOCON_ISCSBN_SHIFT));
+
+	if (spi->mode & SPI_CS_HIGH)
+		gpocon |= (1 << spi->chip_select);
+
+	fgpo = (1 << (spi->chip_select + LTQ_SPI_FGPO_SETOUTN_SHIFT));
+
+	ltq_spi_reg_setbit(hw, gpocon, LTQ_SPI_GPOCON);
+	ltq_spi_reg_setbit(hw, fgpo, LTQ_SPI_FGPO);
+
+	return 0;
+}
+
+static void ltq_spi_cleanup(struct spi_device *spi)
+{
+
+}
+
+static void ltq_spi_txfifo_write(struct ltq_spi *hw)
+{
+	u32 fstat, data;
+	u16 fifo_space;
+
+	/* Determine how much FIFOs are free for TX data */
+	fstat = ltq_spi_reg_read(hw, LTQ_SPI_FSTAT);
+	fifo_space = hw->txfs - ((fstat >> LTQ_SPI_FSTAT_TXFFL_SHIFT) &
+					LTQ_SPI_FSTAT_TXFFL_MASK);
+
+	if (!fifo_space)
+		return;
+
+	while (hw->tx_cnt < hw->len && fifo_space) {
+		data = hw->get_tx(hw);
+		ltq_spi_reg_write(hw, data, LTQ_SPI_TB);
+		fifo_space--;
+	}
+}
+
+static void ltq_spi_rxfifo_read(struct ltq_spi *hw)
+{
+	u32 fstat, data, *rx32;
+	u16 fifo_fill;
+	u8 rxbv, shift, *rx8;
+
+	/* Determine how much FIFOs are filled with RX data */
+	fstat = ltq_spi_reg_read(hw, LTQ_SPI_FSTAT);
+	fifo_fill = ((fstat >> LTQ_SPI_FSTAT_RXFFL_SHIFT)
+			& LTQ_SPI_FSTAT_RXFFL_MASK);
+
+	if (!fifo_fill)
+		return;
+
+	/*
+	 * The 32 bit FIFO is always used completely independent from the
+	 * bits_per_word value. Thus four bytes have to be read at once
+	 * per FIFO.
+	 */
+	rx32 = (u32 *) hw->rx;
+	while (hw->len - hw->rx_cnt >= 4 && fifo_fill) {
+		*rx32++ = ltq_spi_reg_read(hw, LTQ_SPI_RB);
+		hw->rx_cnt += 4;
+		hw->rx += 4;
+		fifo_fill--;
+	}
+
+	/*
+	 * If there are remaining bytes, read byte count from STAT.RXBV
+	 * register and read the data byte-wise.
+	 */
+	while (fifo_fill && hw->rx_cnt < hw->len) {
+		rxbv = (ltq_spi_reg_read(hw, LTQ_SPI_STAT) >>
+			LTQ_SPI_STAT_RXBV_SHIFT) & LTQ_SPI_STAT_RXBV_MASK;
+		data = ltq_spi_reg_read(hw, LTQ_SPI_RB);
+
+		shift = (rxbv - 1) * 8;
+		rx8 = hw->rx;
+
+		while (rxbv) {
+			*rx8++ = (data >> shift) & 0xFF;
+			rxbv--;
+			shift -= 8;
+			hw->rx_cnt++;
+			hw->rx++;
+		}
+
+		fifo_fill--;
+	}
+}
+
+static void ltq_spi_rxreq_set(struct ltq_spi *hw)
+{
+	u32 rxreq, rxreq_max, rxtodo;
+
+	rxtodo = ltq_spi_reg_read(hw, LTQ_SPI_RXCNT) & LTQ_SPI_RXCNT_TODO_MASK;
+
+	/*
+	 * In RX-only mode the serial clock is activated only after writing
+	 * the expected amount of RX bytes into RXREQ register.
+	 * To avoid receive overflows at high clocks it is better to request
+	 * only the amount of bytes that fits into all FIFOs. This value
+	 * depends on the FIFO size implemented in hardware.
+	 */
+	rxreq = hw->len - hw->rx_cnt;
+	rxreq_max = hw->rxfs << 2;
+	rxreq = min(rxreq_max, rxreq);
+
+	if (!rxtodo && rxreq)
+		ltq_spi_reg_write(hw, rxreq, LTQ_SPI_RXREQ);
+}
+
+static inline void ltq_spi_complete(struct ltq_spi *hw)
+{
+	complete(&hw->done);
+}
+
+irqreturn_t ltq_spi_tx_irq(int irq, void *data)
+{
+	struct ltq_spi *hw = data;
+	unsigned long flags;
+	int completed = 0;
+
+	spin_lock_irqsave(&hw->lock, flags);
+
+	if (hw->tx_cnt < hw->len)
+		ltq_spi_txfifo_write(hw);
+
+	if (hw->tx_cnt == hw->len)
+		completed = 1;
+
+	spin_unlock_irqrestore(&hw->lock, flags);
+
+	if (completed)
+		ltq_spi_complete(hw);
+
+	return IRQ_HANDLED;
+}
+
+irqreturn_t ltq_spi_rx_irq(int irq, void *data)
+{
+	struct ltq_spi *hw = data;
+	unsigned long flags;
+	int completed = 0;
+
+	spin_lock_irqsave(&hw->lock, flags);
+
+	if (hw->rx_cnt < hw->len) {
+		ltq_spi_rxfifo_read(hw);
+
+		if (hw->tx && hw->tx_cnt < hw->len)
+			ltq_spi_txfifo_write(hw);
+	}
+
+	if (hw->rx_cnt == hw->len)
+		completed = 1;
+	else if (!hw->tx)
+		ltq_spi_rxreq_set(hw);
+
+	spin_unlock_irqrestore(&hw->lock, flags);
+
+	if (completed)
+		ltq_spi_complete(hw);
+
+	return IRQ_HANDLED;
+}
+
+irqreturn_t ltq_spi_err_irq(int irq, void *data)
+{
+	struct ltq_spi *hw = data;
+	unsigned long flags;
+
+	spin_lock_irqsave(&hw->lock, flags);
+
+	/* Disable all interrupts */
+	ltq_spi_reg_clearbit(hw, LTQ_SPI_IRNEN_ALL, LTQ_SPI_IRNEN);
+
+	dev_err(hw->dev, "error %x\n", ltq_spi_reg_read(hw, LTQ_SPI_STAT));
+
+	/* Clear all error flags */
+	ltq_spi_reg_write(hw, LTQ_SPI_WHBSTATE_CLR_ERRORS, LTQ_SPI_WHBSTATE);
+
+	/* Flush FIFOs */
+	ltq_spi_reg_setbit(hw, LTQ_SPI_RXFCON_RXFLU, LTQ_SPI_RXFCON);
+	ltq_spi_reg_setbit(hw, LTQ_SPI_TXFCON_TXFLU, LTQ_SPI_TXFCON);
+
+	hw->status = -EIO;
+	spin_unlock_irqrestore(&hw->lock, flags);
+
+	ltq_spi_complete(hw);
+
+	return IRQ_HANDLED;
+}
+
+static int ltq_spi_txrx_bufs(struct spi_device *spi, struct spi_transfer *t)
+{
+	struct ltq_spi *hw = ltq_spi_to_hw(spi);
+	u32 irq_flags = 0;
+
+	hw->tx = t->tx_buf;
+	hw->rx = t->rx_buf;
+	hw->len = t->len;
+	hw->tx_cnt = 0;
+	hw->rx_cnt = 0;
+	hw->status = 0;
+	init_completion(&hw->done);
+
+	ltq_spi_xmit_set(hw, t);
+
+	/* Enable error interrupts */
+	ltq_spi_reg_setbit(hw, LTQ_SPI_IRNEN_E, LTQ_SPI_IRNEN);
+
+	if (hw->tx) {
+		/* Initially fill TX FIFO with as much data as possible */
+		ltq_spi_txfifo_write(hw);
+		irq_flags |= hw->irnen_t;
+
+		/* Always enable RX interrupt in Full Duplex mode */
+		if (hw->rx)
+			irq_flags |= hw->irnen_r;
+	} else if (hw->rx) {
+		/* Start RX clock */
+		ltq_spi_rxreq_set(hw);
+
+		/* Enable RX interrupt to receive data from RX FIFOs */
+		irq_flags |= hw->irnen_r;
+	}
+
+	/* Enable TX or RX interrupts */
+	ltq_spi_reg_setbit(hw, irq_flags, LTQ_SPI_IRNEN);
+	wait_for_completion_interruptible(&hw->done);
+
+	/* Disable all interrupts */
+	ltq_spi_reg_clearbit(hw, LTQ_SPI_IRNEN_ALL, LTQ_SPI_IRNEN);
+
+	/*
+	 * Return length of current transfer for bitbang utility code if
+	 * no errors occured during transmission.
+	 */
+	if (!hw->status)
+		hw->status = hw->len;
+
+	return hw->status;
+}
+
+static const struct ltq_spi_irq_map {
+	char *name;
+	irq_handler_t handler;
+} ltq_spi_irqs[] = {
+	{ "spi_rx", ltq_spi_rx_irq },
+	{ "spi_tx", ltq_spi_tx_irq },
+	{ "spi_err", ltq_spi_err_irq },
+};
+
+static int ltq_spi_probe(struct platform_device *pdev)
+{
+	struct resource irqres[3];
+	struct spi_master *master;
+	struct resource *r;
+	struct ltq_spi *hw;
+	int ret, i;
+	u32 data, id;
+
+	if (of_irq_to_resource_table(pdev->dev.of_node, irqres, 3) != 3) {
+		dev_err(&pdev->dev, "IRQ settings missing in device tree\n");
+		return -EINVAL;
+	}
+
+	master = spi_alloc_master(&pdev->dev, sizeof(struct ltq_spi));
+	if (!master) {
+		dev_err(&pdev->dev, "spi_alloc_master\n");
+		ret = -ENOMEM;
+		goto err;
+	}
+
+	hw = spi_master_get_devdata(master);
+
+	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (r == NULL) {
+		dev_err(&pdev->dev, "platform_get_resource\n");
+		ret = -ENOENT;
+		goto err_master;
+	}
+
+	r = devm_request_mem_region(&pdev->dev, r->start, resource_size(r),
+			pdev->name);
+	if (!r) {
+		dev_err(&pdev->dev, "failed to request memory region\n");
+		ret = -ENXIO;
+		goto err_master;
+	}
+
+	hw->base = devm_ioremap_nocache(&pdev->dev, r->start, resource_size(r));
+	if (!hw->base) {
+		dev_err(&pdev->dev, "failed to remap memory region\n");
+		ret = -ENXIO;
+		goto err_master;
+	}
+
+	memset(hw->irq, 0, sizeof(hw->irq));
+	for (i = 0; i < ARRAY_SIZE(ltq_spi_irqs); i++) {
+		hw->irq[i] = irqres[i].start;
+		ret = request_irq(hw->irq[i], ltq_spi_irqs[i].handler,
+				  0, ltq_spi_irqs[i].name, hw);
+		if (ret) {
+			dev_err(&pdev->dev, "failed to request %s irq (%d)\n",
+					ltq_spi_irqs[i].name, hw->irq[i]);
+			goto err_irq;
+		}
+	}
+
+	hw->fpiclk = clk_get_fpi();
+	if (IS_ERR(hw->fpiclk)) {
+		dev_err(&pdev->dev, "failed to get fpi clock\n");
+		ret = PTR_ERR(hw->fpiclk);
+		goto err_clk;
+	}
+
+	hw->spiclk = clk_get(&pdev->dev, NULL);
+	if (IS_ERR(hw->spiclk)) {
+		dev_err(&pdev->dev, "failed to get spi clock gate\n");
+		ret = PTR_ERR(hw->spiclk);
+		goto err_clk;
+	}
+
+	hw->bitbang.master = spi_master_get(master);
+	hw->bitbang.chipselect = ltq_spi_chipselect;
+	hw->bitbang.setup_transfer = ltq_spi_setup_transfer;
+	hw->bitbang.txrx_bufs = ltq_spi_txrx_bufs;
+
+	if (of_machine_is_compatible("lantiq,ase")) {
+		master->num_chipselect = 3;
+
+		hw->irnen_t = LTQ_SPI_IRNEN_T_XWAY;
+		hw->irnen_r = LTQ_SPI_IRNEN_R_XWAY;
+	} else {
+		master->num_chipselect = 6;
+
+		hw->irnen_t = LTQ_SPI_IRNEN_T;
+		hw->irnen_r = LTQ_SPI_IRNEN_R;
+	}
+
+	master->bus_num = pdev->id;
+	master->setup = ltq_spi_setup;
+	master->cleanup = ltq_spi_cleanup;
+	master->dev.of_node = pdev->dev.of_node;
+
+	hw->dev = &pdev->dev;
+	init_completion(&hw->done);
+	spin_lock_init(&hw->lock);
+
+	ltq_spi_hw_enable(hw);
+
+	/* Read module capabilities */
+	id = ltq_spi_reg_read(hw, LTQ_SPI_ID);
+	hw->txfs = (id >> LTQ_SPI_ID_TXFS_SHIFT) & LTQ_SPI_ID_TXFS_MASK;
+	hw->rxfs = (id >> LTQ_SPI_ID_RXFS_SHIFT) & LTQ_SPI_ID_RXFS_MASK;
+	hw->dma_support = (id & LTQ_SPI_ID_CFG) ? 1 : 0;
+
+	ltq_spi_config_mode_set(hw);
+
+	/* Enable error checking, disable TX/RX, set idle value high */
+	data = LTQ_SPI_CON_RUEN | LTQ_SPI_CON_AEN |
+	    LTQ_SPI_CON_TEN | LTQ_SPI_CON_REN |
+	    LTQ_SPI_CON_TXOFF | LTQ_SPI_CON_RXOFF | LTQ_SPI_CON_IDLE;
+	ltq_spi_reg_write(hw, data, LTQ_SPI_CON);
+
+	/* Enable master mode and clear error flags */
+	ltq_spi_reg_write(hw, LTQ_SPI_WHBSTATE_SETMS |
+			  LTQ_SPI_WHBSTATE_CLR_ERRORS, LTQ_SPI_WHBSTATE);
+
+	/* Reset GPIO/CS registers */
+	ltq_spi_reg_write(hw, 0x0, LTQ_SPI_GPOCON);
+	ltq_spi_reg_write(hw, 0xFF00, LTQ_SPI_FGPO);
+
+	/* Enable and flush FIFOs */
+	ltq_spi_reset_fifos(hw);
+
+	ret = spi_bitbang_start(&hw->bitbang);
+	if (ret) {
+		dev_err(&pdev->dev, "spi_bitbang_start failed\n");
+		goto err_bitbang;
+	}
+
+	platform_set_drvdata(pdev, hw);
+
+	pr_info("Lantiq SoC SPI controller rev %u (TXFS %u, RXFS %u, DMA %u)\n",
+		id & LTQ_SPI_ID_REV_MASK, hw->txfs, hw->rxfs, hw->dma_support);
+
+	return 0;
+
+err_bitbang:
+	ltq_spi_hw_disable(hw);
+
+err_clk:
+	if (hw->fpiclk)
+		clk_put(hw->fpiclk);
+	if (hw->spiclk)
+		clk_put(hw->spiclk);
+
+err_irq:
+	clk_put(hw->fpiclk);
+
+	for (; i > 0; i--)
+		free_irq(hw->irq[i], hw);
+
+err_master:
+	spi_master_put(master);
+
+err:
+	return ret;
+}
+
+static int ltq_spi_remove(struct platform_device *pdev)
+{
+	struct ltq_spi *hw = platform_get_drvdata(pdev);
+	int i;
+
+	spi_bitbang_stop(&hw->bitbang);
+
+	platform_set_drvdata(pdev, NULL);
+
+	ltq_spi_config_mode_set(hw);
+	ltq_spi_hw_disable(hw);
+
+	for (i = 0; i < ARRAY_SIZE(hw->irq); i++)
+		if (0 < hw->irq[i])
+			free_irq(hw->irq[i], hw);
+
+	if (hw->fpiclk)
+		clk_put(hw->fpiclk);
+	if (hw->spiclk)
+		clk_put(hw->spiclk);
+
+	spi_master_put(hw->bitbang.master);
+
+	return 0;
+}
+
+static const struct of_device_id ltq_spi_match[] = {
+	{ .compatible = "lantiq,spi-xway" },
+	{},
+};
+MODULE_DEVICE_TABLE(of, ltq_spi_match);
+
+static struct platform_driver ltq_spi_driver = {
+	.probe = ltq_spi_probe,
+	.remove = ltq_spi_remove,
+	.driver = {
+		.name = "spi-xway",
+		.owner = THIS_MODULE,
+		.of_match_table = ltq_spi_match,
+	},
+};
+
+module_platform_driver(ltq_spi_driver);
+
+MODULE_DESCRIPTION("Lantiq SoC SPI controller driver");
+MODULE_AUTHOR("Daniel Schwierzeck <daniel.schwierzeck@googlemail.com>");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:spi-xway");