[PATCH v2 2/2] spi: lantiq-ssc: add support for Lantiq SSC SPI controller

[Hauke Mehrtens <hauke@xxxxxxxxxx>]

This driver supports the Lantiq SSC SPI controller in master
mode. This controller is found on Intel (former Lantiq) SoCs like
the Danube, Falcon, xRX200, xRX300.

Signed-off-by: Daniel Schwierzeck <daniel.schwierzeck@xxxxxxxxx>
Signed-off-by: Hauke Mehrtens <hauke@xxxxxxxxxx>
---
 .../devicetree/bindings/spi/spi-lantiq-ssc.txt     |  29 +
 drivers/spi/Kconfig                                |   8 +
 drivers/spi/Makefile                               |   1 +
 drivers/spi/spi-lantiq-ssc.c                       | 947 +++++++++++++++++++++
 4 files changed, 985 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/spi/spi-lantiq-ssc.txt
 create mode 100644 drivers/spi/spi-lantiq-ssc.c

diff --git a/Documentation/devicetree/bindings/spi/spi-lantiq-ssc.txt b/Documentation/devicetree/bindings/spi/spi-lantiq-ssc.txt
new file mode 100644
index 0000000..6069b95
--- /dev/null
+++ b/Documentation/devicetree/bindings/spi/spi-lantiq-ssc.txt
@@ -0,0 +1,29 @@
+Lantiq Synchronous Serial Controller (SSC) SPI master driver
+
+Required properties:
+- compatible: "lantiq,ase-spi", "lantiq,falcon-spi", "lantiq,xrx100-spi"
+- #address-cells: see spi-bus.txt
+- #size-cells: see spi-bus.txt
+- reg: address and length of the spi master registers
+- interrupts: should contain the "spi_rx", "spi_tx" and "spi_err" interrupt.
+
+
+Optional properties:
+- clocks: spi clock phandle
+- num-cs: see spi-bus.txt, set to 8 if unset
+- base-cs: the number of the first chip select, set to 1 if unset.
+
+Example:
+
+
+spi: spi@E100800 {
+	compatible = "lantiq,xrx200-spi", "lantiq,xrx100-spi";
+	reg = <0xE100800 0x100>;
+	interrupt-parent = <&icu0>;
+	interrupts = <22 23 24>;
+	interrupt-names = "spi_rx", "spi_tx", "spi_err";
+	#address-cells = <1>;
+	#size-cells = <1>;
+	num-cs = <6>;
+	base-cs = <1>;
+};
diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index b799547..7714c3f 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -403,6 +403,14 @@ config SPI_NUC900
 	help
 	  SPI driver for Nuvoton NUC900 series ARM SoCs
 
+config SPI_LANTIQ_SSC
+	tristate "Lantiq SSC SPI controller"
+	depends on LANTIQ
+	help
+	  This driver supports the Lantiq SSC SPI controller in master
+	  mode. This controller is found on Intel (former Lantiq) SoCs like
+	  the Danube, Falcon, xRX200, xRX300.
+
 config SPI_OC_TINY
 	tristate "OpenCores tiny SPI"
 	depends on GPIOLIB || COMPILE_TEST
diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
index aa939d9..43f8551 100644
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -47,6 +47,7 @@ obj-$(CONFIG_SPI_FSL_SPI)		+= spi-fsl-spi.o
 obj-$(CONFIG_SPI_GPIO)			+= spi-gpio.o
 obj-$(CONFIG_SPI_IMG_SPFI)		+= spi-img-spfi.o
 obj-$(CONFIG_SPI_IMX)			+= spi-imx.o
+obj-$(CONFIG_SPI_LANTIQ_SSC)		+= spi-lantiq-ssc.o
 obj-$(CONFIG_SPI_JCORE)			+= spi-jcore.o
 obj-$(CONFIG_SPI_LM70_LLP)		+= spi-lm70llp.o
 obj-$(CONFIG_SPI_LP8841_RTC)		+= spi-lp8841-rtc.o
diff --git a/drivers/spi/spi-lantiq-ssc.c b/drivers/spi/spi-lantiq-ssc.c
new file mode 100644
index 0000000..2b3f0de
--- /dev/null
+++ b/drivers/spi/spi-lantiq-ssc.c
@@ -0,0 +1,947 @@
+/*
+ * Copyright (C) 2011-2015 Daniel Schwierzeck <daniel.schwierzeck@xxxxxxxxx>
+ * Copyright (C) 2016 Hauke Mehrtens <hauke@xxxxxxxxxx>
+ *
+ * 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/kernel.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/clk.h>
+#include <linux/io.h>
+#include <linux/delay.h>
+#include <linux/interrupt.h>
+#include <linux/sched.h>
+#include <linux/completion.h>
+#include <linux/spinlock.h>
+#include <linux/err.h>
+#include <linux/gpio.h>
+#include <linux/pm_runtime.h>
+#include <linux/spi/spi.h>
+
+#include <lantiq_soc.h>
+
+#define SPI_RX_IRQ_NAME		"spi_rx"
+#define SPI_TX_IRQ_NAME		"spi_tx"
+#define SPI_ERR_IRQ_NAME	"spi_err"
+#define SPI_FRM_IRQ_NAME	"spi_frm"
+
+#define SPI_CLC			0x00
+#define SPI_PISEL		0x04
+#define SPI_ID			0x08
+#define SPI_CON			0x10
+#define SPI_STAT		0x14
+#define SPI_WHBSTATE		0x18
+#define SPI_TB			0x20
+#define SPI_RB			0x24
+#define SPI_RXFCON		0x30
+#define SPI_TXFCON		0x34
+#define SPI_FSTAT		0x38
+#define SPI_BRT			0x40
+#define SPI_BRSTAT		0x44
+#define SPI_SFCON		0x60
+#define SPI_SFSTAT		0x64
+#define SPI_GPOCON		0x70
+#define SPI_GPOSTAT		0x74
+#define SPI_FPGO		0x78
+#define SPI_RXREQ		0x80
+#define SPI_RXCNT		0x84
+#define SPI_DMACON		0xec
+#define SPI_IRNEN		0xf4
+#define SPI_IRNICR		0xf8
+#define SPI_IRNCR		0xfc
+
+#define SPI_CLC_SMC_S		16	/* Clock divider for sleep mode */
+#define SPI_CLC_SMC_M		(0xFF << SPI_CLC_SMC_S)
+#define SPI_CLC_RMC_S		8	/* Clock divider for normal run mode */
+#define SPI_CLC_RMC_M		(0xFF << SPI_CLC_RMC_S)
+#define SPI_CLC_DISS		BIT(1)	/* Disable status bit */
+#define SPI_CLC_DISR		BIT(0)	/* Disable request bit */
+
+#define SPI_ID_TXFS_S		24	/* Implemented TX FIFO size */
+#define SPI_ID_TXFS_M		(0x3F << SPI_ID_TXFS_S)
+#define SPI_ID_RXFS_S		16	/* Implemented RX FIFO size */
+#define SPI_ID_RXFS_M		(0x3F << SPI_ID_RXFS_S)
+#define SPI_ID_MOD_S		8	/* Module ID */
+#define SPI_ID_MOD_M		(0xff << SPI_ID_MOD_S)
+#define SPI_ID_CFG_S		5	/* DMA interface support */
+#define SPI_ID_CFG_M		(1 << SPI_ID_CFG_S)
+#define SPI_ID_REV_M		0x1F	/* Hardware revision number */
+
+#define SPI_CON_BM_S		16	/* Data width selection */
+#define SPI_CON_BM_M		(0x1F << SPI_CON_BM_S)
+#define SPI_CON_EM		BIT(24)	/* Echo mode */
+#define SPI_CON_IDLE		BIT(23)	/* Idle bit value */
+#define SPI_CON_ENBV		BIT(22)	/* Enable byte valid control */
+#define SPI_CON_RUEN		BIT(12)	/* Receive underflow error enable */
+#define SPI_CON_TUEN		BIT(11)	/* Transmit underflow error enable */
+#define SPI_CON_AEN		BIT(10)	/* Abort error enable */
+#define SPI_CON_REN		BIT(9)	/* Receive overflow error enable */
+#define SPI_CON_TEN		BIT(8)	/* Transmit overflow error enable */
+#define SPI_CON_LB		BIT(7)	/* Loopback control */
+#define SPI_CON_PO		BIT(6)	/* Clock polarity control */
+#define SPI_CON_PH		BIT(5)	/* Clock phase control */
+#define SPI_CON_HB		BIT(4)	/* Heading control */
+#define SPI_CON_RXOFF		BIT(1)	/* Switch receiver off */
+#define SPI_CON_TXOFF		BIT(0)	/* Switch transmitter off */
+
+#define SPI_STAT_RXBV_S		28
+#define SPI_STAT_RXBV_M		(0x7 << SPI_STAT_RXBV_S)
+#define SPI_STAT_BSY		BIT(13)	/* Busy flag */
+#define SPI_STAT_RUE		BIT(12)	/* Receive underflow error flag */
+#define SPI_STAT_TUE		BIT(11)	/* Transmit underflow error flag */
+#define SPI_STAT_AE		BIT(10)	/* Abort error flag */
+#define SPI_STAT_RE		BIT(9)	/* Receive error flag */
+#define SPI_STAT_TE		BIT(8)	/* Transmit error flag */
+#define SPI_STAT_ME		BIT(7)	/* Mode error flag */
+#define SPI_STAT_MS		BIT(1)	/* Master/slave select bit */
+#define SPI_STAT_EN		BIT(0)	/* Enable bit */
+
+#define SPI_WHBSTATE_SETTUE	BIT(15)	/* Set transmit underflow error flag */
+#define SPI_WHBSTATE_SETAE	BIT(14)	/* Set abort error flag */
+#define SPI_WHBSTATE_SETRE	BIT(13)	/* Set receive error flag */
+#define SPI_WHBSTATE_SETTE	BIT(12)	/* Set transmit error flag */
+#define SPI_WHBSTATE_CLRTUE	BIT(11)	/* Clear transmit underflow error flag */
+#define SPI_WHBSTATE_CLRAE	BIT(10)	/* Clear abort error flag */
+#define SPI_WHBSTATE_CLRRE	BIT(9)	/* Clear receive error flag */
+#define SPI_WHBSTATE_CLRTE	BIT(8)	/* Clear transmit error flag */
+#define SPI_WHBSTATE_SETME	BIT(7)	/* Set mode error flag */
+#define SPI_WHBSTATE_CLRME	BIT(6)	/* Clear mode error flag */
+#define SPI_WHBSTATE_SETRUE	BIT(5)	/* Set receive underflow error flag */
+#define SPI_WHBSTATE_CLRRUE	BIT(4)	/* Clear receive underflow error flag */
+#define SPI_WHBSTATE_SETMS	BIT(3)	/* Set master select bit */
+#define SPI_WHBSTATE_CLRMS	BIT(2)	/* Clear master select bit */
+#define SPI_WHBSTATE_SETEN	BIT(1)	/* Set enable bit (operational mode) */
+#define SPI_WHBSTATE_CLREN	BIT(0)	/* Clear enable bit (config mode */
+#define SPI_WHBSTATE_CLR_ERRORS	0x0F50
+
+#define SPI_RXFCON_RXFITL_S	8	/* FIFO interrupt trigger level */
+#define SPI_RXFCON_RXFITL_M	(0x3F << SPI_RXFCON_RXFITL_S)
+#define SPI_RXFCON_RXFLU	BIT(1)	/* FIFO flush */
+#define SPI_RXFCON_RXFEN	BIT(0)	/* FIFO enable */
+
+#define SPI_TXFCON_TXFITL_S	8	/* FIFO interrupt trigger level */
+#define SPI_TXFCON_TXFITL_M	(0x3F << SPI_TXFCON_TXFITL_S)
+#define SPI_TXFCON_TXFLU	BIT(1)	/* FIFO flush */
+#define SPI_TXFCON_TXFEN	BIT(0)	/* FIFO enable */
+
+#define SPI_FSTAT_RXFFL_S	0
+#define SPI_FSTAT_RXFFL_M	(0x3f << SPI_FSTAT_RXFFL_S)
+#define SPI_FSTAT_TXFFL_S	8
+#define SPI_FSTAT_TXFFL_M	(0x3f << SPI_FSTAT_TXFFL_S)
+
+#define SPI_GPOCON_ISCSBN_S	8
+#define SPI_GPOCON_INVOUTN_S	0
+
+#define SPI_FGPO_SETOUTN_S	8
+#define SPI_FGPO_CLROUTN_S	0
+
+#define SPI_RXREQ_RXCNT_M	0xFFFF	/* Receive count value */
+#define SPI_RXCNT_TODO_M	0xFFFF	/* Recevie to-do value */
+
+#define SPI_IRNEN_TFI		BIT(4)	/* TX finished interrupt */
+#define SPI_IRNEN_F		BIT(3)	/* Frame end interrupt request */
+#define SPI_IRNEN_E		BIT(2)	/* Error end interrupt request */
+#define SPI_IRNEN_T_XWAY	BIT(1)	/* Transmit end interrupt request */
+#define SPI_IRNEN_R_XWAY	BIT(0)	/* Receive end interrupt request */
+#define SPI_IRNEN_R_XRX		BIT(1)	/* Transmit end interrupt request */
+#define SPI_IRNEN_T_XRX		BIT(0)	/* Receive end interrupt request */
+#define SPI_IRNEN_ALL		0x1F
+
+struct lantiq_ssc_hwcfg {
+	unsigned int irnen_r;
+	unsigned int irnen_t;
+};
+
+struct lantiq_ssc_spi {
+	struct spi_master		*master;
+	struct device			*dev;
+	void __iomem			*regbase;
+	struct clk			*spi_clk;
+	struct clk			*fpi_clk;
+	const struct lantiq_ssc_hwcfg	*hwcfg;
+
+	spinlock_t			lock;
+
+	const u8			*tx;
+	u8				*rx;
+	unsigned int			tx_todo;
+	unsigned int			rx_todo;
+	unsigned int			bits_per_word;
+	unsigned int			speed_hz;
+	int				status;
+	unsigned int			tx_fifo_size;
+	unsigned int			rx_fifo_size;
+	unsigned int			base_cs;
+};
+
+static u32 lantiq_ssc_readl(const struct lantiq_ssc_spi *spi, u32 reg)
+{
+	return __raw_readl(spi->regbase + reg);
+}
+
+static void lantiq_ssc_writel(const struct lantiq_ssc_spi *spi, u32 val,
+			      u32 reg)
+{
+	__raw_writel(val, spi->regbase + reg);
+}
+
+static void lantiq_ssc_maskl(const struct lantiq_ssc_spi *spi, u32 clr,
+			     u32 set, u32 reg)
+{
+	u32 val = __raw_readl(spi->regbase + reg);
+
+	val &= ~clr;
+	val |= set;
+	__raw_writel(val, spi->regbase + reg);
+}
+
+static unsigned int tx_fifo_level(const struct lantiq_ssc_spi *spi)
+{
+	u32 fstat = lantiq_ssc_readl(spi, SPI_FSTAT);
+
+	return (fstat & SPI_FSTAT_TXFFL_M) >> SPI_FSTAT_TXFFL_S;
+}
+
+static unsigned int rx_fifo_level(const struct lantiq_ssc_spi *spi)
+{
+	u32 fstat = lantiq_ssc_readl(spi, SPI_FSTAT);
+
+	return fstat & SPI_FSTAT_RXFFL_M;
+}
+
+static unsigned int tx_fifo_free(const struct lantiq_ssc_spi *spi)
+{
+	return spi->tx_fifo_size - tx_fifo_level(spi);
+}
+
+static void rx_fifo_reset(const struct lantiq_ssc_spi *spi)
+{
+	u32 val = spi->rx_fifo_size << SPI_RXFCON_RXFITL_S;
+
+	val |= SPI_RXFCON_RXFEN | SPI_RXFCON_RXFLU;
+	lantiq_ssc_writel(spi, val, SPI_RXFCON);
+}
+
+static void tx_fifo_reset(const struct lantiq_ssc_spi *spi)
+{
+	u32 val = 1 << SPI_TXFCON_TXFITL_S;
+
+	val |= SPI_TXFCON_TXFEN | SPI_TXFCON_TXFLU;
+	lantiq_ssc_writel(spi, val, SPI_TXFCON);
+}
+
+static void rx_fifo_flush(const struct lantiq_ssc_spi *spi)
+{
+	lantiq_ssc_maskl(spi, 0, SPI_RXFCON_RXFLU, SPI_RXFCON);
+}
+
+static void tx_fifo_flush(const struct lantiq_ssc_spi *spi)
+{
+	lantiq_ssc_maskl(spi, 0, SPI_TXFCON_TXFLU, SPI_TXFCON);
+}
+
+static void hw_enter_config_mode(const struct lantiq_ssc_spi *spi)
+{
+	lantiq_ssc_writel(spi, SPI_WHBSTATE_CLREN, SPI_WHBSTATE);
+}
+
+static void hw_enter_active_mode(const struct lantiq_ssc_spi *spi)
+{
+	lantiq_ssc_writel(spi, SPI_WHBSTATE_SETEN, SPI_WHBSTATE);
+}
+
+static void hw_setup_speed_hz(const struct lantiq_ssc_spi *spi,
+			      unsigned int max_speed_hz)
+{
+	u32 spi_clk, brt;
+
+	/*
+	 * SPI module clock is derived from FPI bus clock dependent on
+	 * divider value in CLC.RMS which is always set to 1.
+	 *
+	 *                 f_SPI
+	 * baudrate = --------------
+	 *             2 * (BR + 1)
+	 */
+	spi_clk = clk_get_rate(spi->fpi_clk) / 2;
+
+	if (max_speed_hz > spi_clk)
+		brt = 0;
+	else
+		brt = spi_clk / max_speed_hz - 1;
+
+	if (brt > 0xFFFF)
+		brt = 0xFFFF;
+
+	dev_dbg(spi->dev, "spi_clk %u, max_speed_hz %u, brt %u\n",
+		spi_clk, max_speed_hz, brt);
+
+	lantiq_ssc_writel(spi, brt, SPI_BRT);
+}
+
+static void hw_setup_bits_per_word(const struct lantiq_ssc_spi *spi,
+				   unsigned int bits_per_word)
+{
+	u32 bm;
+
+	/* CON.BM value = bits_per_word - 1 */
+	bm = (bits_per_word - 1) << SPI_CON_BM_S;
+
+	lantiq_ssc_maskl(spi, SPI_CON_BM_M, bm, SPI_CON);
+}
+
+static void hw_setup_clock_mode(const struct lantiq_ssc_spi *spi,
+				unsigned int mode)
+{
+	u32 con_set = 0, con_clr = 0;
+
+	/*
+	 * 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 (mode & SPI_CPHA)
+		con_clr |= SPI_CON_PH;
+	else
+		con_set |= SPI_CON_PH;
+
+	if (mode & SPI_CPOL)
+		con_set |= SPI_CON_PO | SPI_CON_IDLE;
+	else
+		con_clr |= SPI_CON_PO | SPI_CON_IDLE;
+
+	/* Set heading control */
+	if (mode & SPI_LSB_FIRST)
+		con_clr |= SPI_CON_HB;
+	else
+		con_set |= SPI_CON_HB;
+
+	/* Set loopback mode */
+	if (mode & SPI_LOOP)
+		con_set |= SPI_CON_LB;
+	else
+		con_clr |= SPI_CON_LB;
+
+	lantiq_ssc_maskl(spi, con_clr, con_set, SPI_CON);
+}
+
+static void lantiq_ssc_hw_init(const struct lantiq_ssc_spi *spi)
+{
+	const struct lantiq_ssc_hwcfg *hwcfg = spi->hwcfg;
+
+	/*
+	 * Set clock divider for run mode to 1 to
+	 * run at same frequency as FPI bus
+	 */
+	lantiq_ssc_writel(spi, 1 << SPI_CLC_RMC_S, SPI_CLC);
+
+	/* Put controller into config mode */
+	hw_enter_config_mode(spi);
+
+	/* Clear error flags */
+	lantiq_ssc_maskl(spi, 0, SPI_WHBSTATE_CLR_ERRORS, SPI_WHBSTATE);
+
+	/* Enable error checking, disable TX/RX */
+	lantiq_ssc_writel(spi, SPI_CON_RUEN | SPI_CON_AEN | SPI_CON_TEN |
+		SPI_CON_REN | SPI_CON_TXOFF | SPI_CON_RXOFF, SPI_CON);
+
+	/* Setup default SPI mode */
+	hw_setup_bits_per_word(spi, spi->bits_per_word);
+	hw_setup_clock_mode(spi, SPI_MODE_0);
+
+	/* Enable master mode and clear error flags */
+	lantiq_ssc_writel(spi, SPI_WHBSTATE_SETMS | SPI_WHBSTATE_CLR_ERRORS,
+			       SPI_WHBSTATE);
+
+	/* Reset GPIO/CS registers */
+	lantiq_ssc_writel(spi, 0, SPI_GPOCON);
+	lantiq_ssc_writel(spi, 0xFF00, SPI_FPGO);
+
+	/* Enable and flush FIFOs */
+	rx_fifo_reset(spi);
+	tx_fifo_reset(spi);
+
+	/* Enable interrupts */
+	lantiq_ssc_writel(spi, hwcfg->irnen_t | hwcfg->irnen_r | SPI_IRNEN_E,
+			  SPI_IRNEN);
+}
+
+static int lantiq_ssc_setup(struct spi_device *spidev)
+{
+	struct spi_master *master = spidev->master;
+	struct lantiq_ssc_spi *spi = spi_master_get_devdata(master);
+	unsigned int cs = spidev->chip_select;
+	u32 gpocon;
+
+	/* GPIOs are used for CS */
+	if (gpio_is_valid(spidev->cs_gpio))
+		return 0;
+
+	dev_dbg(spi->dev, "using internal chipselect %u\n", cs);
+
+	if (cs < spi->base_cs) {
+		dev_err(spi->dev,
+			"chipselect %i too small (min %i)\n", cs, spi->base_cs);
+		return -EINVAL;
+	}
+
+	/* set GPO pin to CS mode */
+	gpocon = 1 << ((cs - spi->base_cs) + SPI_GPOCON_ISCSBN_S);
+
+	/* invert GPO pin */
+	if (spidev->mode & SPI_CS_HIGH)
+		gpocon |= 1 << (cs - spi->base_cs);
+
+	lantiq_ssc_maskl(spi, 0, gpocon, SPI_GPOCON);
+
+	return 0;
+}
+
+static int lantiq_ssc_prepare_message(struct spi_master *master,
+				      struct spi_message *message)
+{
+	struct lantiq_ssc_spi *spi = spi_master_get_devdata(master);
+
+	hw_enter_config_mode(spi);
+	hw_setup_clock_mode(spi, message->spi->mode);
+	hw_enter_active_mode(spi);
+
+	return 0;
+}
+
+static void hw_setup_transfer(struct lantiq_ssc_spi *spi,
+			      struct spi_device *spidev, struct spi_transfer *t)
+{
+	unsigned int speed_hz, bits_per_word;
+	u32 con;
+
+	if (t->speed_hz)
+		speed_hz = t->speed_hz;
+	else
+		speed_hz = spidev->max_speed_hz;
+
+	if (t->bits_per_word)
+		bits_per_word = t->bits_per_word;
+	else
+		bits_per_word = spidev->bits_per_word;
+
+	if (bits_per_word != spi->bits_per_word ||
+		speed_hz != spi->speed_hz) {
+		hw_enter_config_mode(spi);
+		hw_setup_speed_hz(spi, speed_hz);
+		hw_setup_bits_per_word(spi, bits_per_word);
+		hw_enter_active_mode(spi);
+
+		spi->speed_hz = speed_hz;
+		spi->bits_per_word = bits_per_word;
+	}
+
+	/* Configure transmitter and receiver */
+	con = lantiq_ssc_readl(spi, SPI_CON);
+	if (t->tx_buf)
+		con &= ~SPI_CON_TXOFF;
+	else
+		con |= SPI_CON_TXOFF;
+
+	if (t->rx_buf)
+		con &= ~SPI_CON_RXOFF;
+	else
+		con |= SPI_CON_RXOFF;
+
+	lantiq_ssc_writel(spi, con, SPI_CON);
+}
+
+static int lantiq_ssc_unprepare_message(struct spi_master *master,
+					struct spi_message *message)
+{
+	struct lantiq_ssc_spi *spi = spi_master_get_devdata(master);
+
+	/* Disable transmitter and receiver while idle */
+	lantiq_ssc_maskl(spi, 0, SPI_CON_TXOFF | SPI_CON_RXOFF, SPI_CON);
+
+	return 0;
+}
+
+static void tx_fifo_write(struct lantiq_ssc_spi *spi)
+{
+	const u8 *tx8;
+	const u16 *tx16;
+	const u32 *tx32;
+	u32 data;
+	unsigned int tx_free = tx_fifo_free(spi);
+
+	while (spi->tx_todo && tx_free) {
+		switch (spi->bits_per_word) {
+		case 2 ... 8:
+			tx8 = spi->tx;
+			data = *tx8;
+			spi->tx_todo--;
+			spi->tx++;
+			break;
+		case 16:
+			tx16 = (u16 *) spi->tx;
+			data = *tx16;
+			spi->tx_todo -= 2;
+			spi->tx += 2;
+			break;
+		case 24:
+		case 32:
+			tx32 = (u32 *) spi->tx;
+			data = *tx32;
+			spi->tx_todo -= 4;
+			spi->tx += 4;
+			break;
+		default:
+			WARN_ON(1);
+			data = 0;
+		}
+
+		lantiq_ssc_writel(spi, data, SPI_TB);
+		tx_free--;
+	}
+}
+
+static void rx_fifo_read_full_duplex(struct lantiq_ssc_spi *spi)
+{
+	u8 *rx8;
+	u16 *rx16;
+	u32 *rx32;
+	u32 data;
+	unsigned int rx_fill = rx_fifo_level(spi);
+
+	while (rx_fill) {
+		data = lantiq_ssc_readl(spi, SPI_RB);
+
+		switch (spi->bits_per_word) {
+		case 2 ... 8:
+			rx8 = spi->rx;
+			*rx8 = data;
+			spi->rx_todo--;
+			spi->rx++;
+			break;
+		case 16:
+			rx16 = (u16 *) spi->rx;
+			*rx16 = data;
+			spi->rx_todo -= 2;
+			spi->rx += 2;
+			break;
+		case 24:
+		case 32:
+			rx32 = (u32 *) spi->rx;
+			*rx32 = data;
+			spi->rx_todo -= 4;
+			spi->rx += 4;
+			break;
+		default:
+			WARN_ON(1);
+		}
+
+		rx_fill--;
+	}
+}
+
+static void rx_fifo_read_half_duplex(struct lantiq_ssc_spi *spi)
+{
+	u32 data, *rx32;
+	u8 *rx8;
+	unsigned int rxbv, shift;
+	unsigned int rx_fill = rx_fifo_level(spi);
+
+	/*
+	 * In RX-only mode the bits per word value is ignored by HW. A value
+	 * of 32 is used instead. Thus all 4 bytes per FIFO must be read.
+	 * If remaining RX bytes are less than 4, the FIFO must be read
+	 * differently. The amount of received and valid bytes is indicated
+	 * by STAT.RXBV register value.
+	 */
+	while (rx_fill) {
+		if (spi->rx_todo < 4)  {
+			rxbv = (lantiq_ssc_readl(spi, SPI_STAT) &
+				SPI_STAT_RXBV_M) >> SPI_STAT_RXBV_S;
+			data = lantiq_ssc_readl(spi, SPI_RB);
+
+			shift = (rxbv - 1) * 8;
+			rx8 = spi->rx;
+
+			while (rxbv) {
+				*rx8++ = (data >> shift) & 0xFF;
+				rxbv--;
+				shift -= 8;
+				spi->rx_todo--;
+				spi->rx++;
+			}
+		} else {
+			data = lantiq_ssc_readl(spi, SPI_RB);
+			rx32 = (u32 *) spi->rx;
+
+			*rx32++ = data;
+			spi->rx_todo -= 4;
+			spi->rx += 4;
+		}
+		rx_fill--;
+	}
+}
+
+static void rx_request(struct lantiq_ssc_spi *spi)
+{
+	unsigned int rxreq, rxreq_max;
+
+	/*
+	 * 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 = spi->rx_todo;
+	rxreq_max = spi->rx_fifo_size * 4;
+	if (rxreq > rxreq_max)
+		rxreq = rxreq_max;
+
+	lantiq_ssc_writel(spi, rxreq, SPI_RXREQ);
+}
+
+static irqreturn_t lantiq_ssc_xmit_interrupt(int irq, void *data)
+{
+	struct lantiq_ssc_spi *spi = data;
+
+	if (spi->tx) {
+		if (spi->rx && spi->rx_todo)
+			rx_fifo_read_full_duplex(spi);
+
+		if (spi->tx_todo)
+			tx_fifo_write(spi);
+		else
+			goto completed;
+	} else if (spi->rx) {
+		if (spi->rx_todo) {
+			rx_fifo_read_half_duplex(spi);
+
+			if (spi->rx_todo)
+				rx_request(spi);
+			else
+				goto completed;
+		} else {
+			goto completed;
+		}
+	}
+
+	return IRQ_HANDLED;
+
+completed:
+	spi->status = 0;
+	spi_finalize_current_transfer(spi->master);
+
+	return IRQ_HANDLED;
+}
+
+static irqreturn_t lantiq_ssc_err_interrupt(int irq, void *data)
+{
+	struct lantiq_ssc_spi *spi = data;
+	u32 stat = lantiq_ssc_readl(spi, SPI_STAT);
+
+	if (stat & SPI_STAT_RUE)
+		dev_err(spi->dev, "receive underflow error\n");
+	if (stat & SPI_STAT_TUE)
+		dev_err(spi->dev, "transmit underflow error\n");
+	if (stat & SPI_STAT_RE)
+		dev_err(spi->dev, "receive overflow error\n");
+	if (stat & SPI_STAT_TE)
+		dev_err(spi->dev, "transmit overflow error\n");
+	if (stat & SPI_STAT_ME)
+		dev_err(spi->dev, "mode error\n");
+
+	/* Clear error flags */
+	lantiq_ssc_maskl(spi, 0, SPI_WHBSTATE_CLR_ERRORS, SPI_WHBSTATE);
+
+	/* set bad status so it can be retried */
+	spi->status = -EIO;
+	spi_finalize_current_transfer(spi->master);
+
+	return IRQ_HANDLED;
+}
+
+static int transfer_start(struct lantiq_ssc_spi *spi, struct spi_device *spidev,
+			  struct spi_transfer *t)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&spi->lock, flags);
+
+	spi->tx = t->tx_buf;
+	spi->rx = t->rx_buf;
+	spi->status = -EINPROGRESS;
+
+	if (t->tx_buf) {
+		spi->tx_todo = t->len;
+
+		/* initially fill TX FIFO */
+		tx_fifo_write(spi);
+	}
+
+	if (spi->rx) {
+		spi->rx_todo = t->len;
+
+		/* start shift clock in RX-only mode */
+		if (!spi->tx)
+			rx_request(spi);
+	}
+
+	spin_unlock_irqrestore(&spi->lock, flags);
+
+	return t->len;
+}
+
+static int lantiq_ssc_check_finished(struct spi_master *master,
+				     unsigned long timeout)
+{
+	struct lantiq_ssc_spi *spi = spi_master_get_devdata(master);
+	unsigned long end;
+
+	/* make sure that HW is idle */
+	end = jiffies + timeout;
+	do {
+		u32 stat = lantiq_ssc_readl(spi, SPI_STAT);
+
+		if (!(stat & SPI_STAT_BSY))
+			return spi->status;
+
+		cond_resched();
+	} while (!time_after_eq(jiffies, end));
+
+	return -ETIMEDOUT;
+}
+
+static void lantiq_ssc_handle_err(struct spi_master *master,
+				  struct spi_message *message)
+{
+	struct lantiq_ssc_spi *spi = spi_master_get_devdata(master);
+
+	/* flush FIFOs on timeout */
+	rx_fifo_flush(spi);
+	tx_fifo_flush(spi);
+}
+
+static void lantiq_ssc_set_cs(struct spi_device *spidev, bool enable)
+{
+	struct lantiq_ssc_spi *spi = spi_master_get_devdata(spidev->master);
+	unsigned int cs = spidev->chip_select;
+	u32 fgpo;
+
+	if (!!(spidev->mode & SPI_CS_HIGH) == enable)
+		fgpo = (1 << (cs - spi->base_cs));
+	else
+		fgpo = (1 << (cs - spi->base_cs + SPI_FGPO_SETOUTN_S));
+
+	lantiq_ssc_writel(spi, fgpo, SPI_FPGO);
+}
+
+static int lantiq_ssc_transfer_one(struct spi_master *master,
+				   struct spi_device *spidev,
+				   struct spi_transfer *t)
+{
+	struct lantiq_ssc_spi *spi = spi_master_get_devdata(master);
+
+	hw_setup_transfer(spi, spidev, t);
+
+	return transfer_start(spi, spidev, t);
+}
+
+static const struct lantiq_ssc_hwcfg lantiq_ssc_xway = {
+	.irnen_r = SPI_IRNEN_R_XWAY,
+	.irnen_t = SPI_IRNEN_T_XWAY,
+};
+
+static const struct lantiq_ssc_hwcfg lantiq_ssc_xrx = {
+	.irnen_r = SPI_IRNEN_R_XRX,
+	.irnen_t = SPI_IRNEN_T_XRX,
+};
+
+static const struct of_device_id lantiq_ssc_match[] = {
+	{ .compatible = "lantiq,ase-spi", .data = &lantiq_ssc_xway, },
+	{ .compatible = "lantiq,falcon-spi", .data = &lantiq_ssc_xrx, },
+	{ .compatible = "lantiq,xrx100-spi", .data = &lantiq_ssc_xrx, },
+	{},
+};
+MODULE_DEVICE_TABLE(of, lantiq_ssc_match);
+
+static int lantiq_ssc_probe(struct platform_device *pdev)
+{
+	struct spi_master *master;
+	struct resource *res;
+	struct lantiq_ssc_spi *spi;
+	const struct lantiq_ssc_hwcfg *hwcfg;
+	const struct of_device_id *match;
+	int err, rx_irq, tx_irq, err_irq;
+	u32 id, supports_dma, revision;
+	unsigned int num_cs;
+
+	match = of_match_device(lantiq_ssc_match, &pdev->dev);
+	if (!match) {
+		dev_err(&pdev->dev, "no device match\n");
+		return -EINVAL;
+	}
+	hwcfg = match->data;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res) {
+		dev_err(&pdev->dev, "failed to get resources\n");
+		return -ENXIO;
+	}
+
+	rx_irq = platform_get_irq_byname(pdev, SPI_RX_IRQ_NAME);
+	if (rx_irq < 0) {
+		dev_err(&pdev->dev, "failed to get %s\n", SPI_RX_IRQ_NAME);
+		return -ENXIO;
+	}
+
+	tx_irq = platform_get_irq_byname(pdev, SPI_TX_IRQ_NAME);
+	if (tx_irq < 0) {
+		dev_err(&pdev->dev, "failed to get %s\n", SPI_TX_IRQ_NAME);
+		return -ENXIO;
+	}
+
+	err_irq = platform_get_irq_byname(pdev, SPI_ERR_IRQ_NAME);
+	if (err_irq < 0) {
+		dev_err(&pdev->dev, "failed to get %s\n", SPI_ERR_IRQ_NAME);
+		return -ENXIO;
+	}
+
+	master = spi_alloc_master(&pdev->dev, sizeof(struct lantiq_ssc_spi));
+	if (!master)
+		return -ENOMEM;
+
+	spi = spi_master_get_devdata(master);
+	spi->master = master;
+	spi->dev = &pdev->dev;
+	spi->hwcfg = hwcfg;
+	platform_set_drvdata(pdev, spi);
+
+	spi->regbase = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(spi->regbase)) {
+		err = PTR_ERR(spi->regbase);
+		goto err_master_put;
+	}
+
+	err = devm_request_irq(&pdev->dev, rx_irq, lantiq_ssc_xmit_interrupt,
+			       0, SPI_RX_IRQ_NAME, spi);
+	if (err)
+		goto err_master_put;
+
+	err = devm_request_irq(&pdev->dev, tx_irq, lantiq_ssc_xmit_interrupt,
+			       0, SPI_TX_IRQ_NAME, spi);
+	if (err)
+		goto err_master_put;
+
+	err = devm_request_irq(&pdev->dev, err_irq, lantiq_ssc_err_interrupt,
+			       0, SPI_ERR_IRQ_NAME, spi);
+	if (err)
+		goto err_master_put;
+
+	spi->spi_clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(spi->spi_clk)) {
+		err = PTR_ERR(spi->spi_clk);
+		goto err_master_put;
+	}
+	err = clk_prepare_enable(spi->spi_clk);
+	if (err)
+		goto err_master_put;
+
+	spi->fpi_clk = clk_get_fpi();
+	if (IS_ERR(spi->fpi_clk)) {
+		err = PTR_ERR(spi->fpi_clk);
+		goto err_clk_disable;
+	}
+
+	num_cs = 8;
+	of_property_read_u32(pdev->dev.of_node, "num-cs", &num_cs);
+
+	spi->base_cs = 1;
+	of_property_read_u32(pdev->dev.of_node, "base-cs", &spi->base_cs);
+
+	spin_lock_init(&spi->lock);
+	spi->bits_per_word = 8;
+	spi->speed_hz = 0;
+
+	master->dev.of_node = pdev->dev.of_node;
+	master->num_chipselect = num_cs;
+	master->setup = lantiq_ssc_setup;
+	master->set_cs = lantiq_ssc_set_cs;
+	master->handle_err = lantiq_ssc_handle_err;
+	master->prepare_message = lantiq_ssc_prepare_message;
+	master->unprepare_message = lantiq_ssc_unprepare_message;
+	master->transfer_one = lantiq_ssc_transfer_one;
+	master->check_finished = lantiq_ssc_check_finished;
+	master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_LSB_FIRST | SPI_CS_HIGH |
+				SPI_LOOP;
+	master->bits_per_word_mask = SPI_BPW_RANGE_MASK(2, 8) |
+				     SPI_BPW_MASK(16) | SPI_BPW_MASK(24) |
+				     SPI_BPW_MASK(32);
+
+	id = lantiq_ssc_readl(spi, SPI_ID);
+	spi->tx_fifo_size = (id & SPI_ID_TXFS_M) >> SPI_ID_TXFS_S;
+	spi->rx_fifo_size = (id & SPI_ID_RXFS_M) >> SPI_ID_RXFS_S;
+	supports_dma = (id & SPI_ID_CFG_M) >> SPI_ID_CFG_S;
+	revision = id & SPI_ID_REV_M;
+
+	lantiq_ssc_hw_init(spi);
+
+	dev_info(&pdev->dev,
+		"Lantiq SSC SPI controller (Rev %i, TXFS %u, RXFS %u, DMA %u)\n",
+		revision, spi->tx_fifo_size, spi->rx_fifo_size, supports_dma);
+
+	err = devm_spi_register_master(&pdev->dev, master);
+	if (err) {
+		dev_err(&pdev->dev, "failed to register spi_master\n");
+		goto err_clk_put;
+	}
+
+	return 0;
+
+err_clk_put:
+	clk_put(spi->fpi_clk);
+err_clk_disable:
+	clk_disable_unprepare(spi->spi_clk);
+err_master_put:
+	spi_master_put(master);
+
+	return err;
+}
+
+static int lantiq_ssc_remove(struct platform_device *pdev)
+{
+	struct lantiq_ssc_spi *spi = platform_get_drvdata(pdev);
+
+	lantiq_ssc_writel(spi, 0, SPI_IRNEN);
+	lantiq_ssc_writel(spi, 0, SPI_CLC);
+	rx_fifo_flush(spi);
+	tx_fifo_flush(spi);
+	hw_enter_config_mode(spi);
+
+	clk_disable_unprepare(spi->spi_clk);
+	clk_put(spi->fpi_clk);
+
+	return 0;
+}
+
+static struct platform_driver lantiq_ssc_driver = {
+	.probe = lantiq_ssc_probe,
+	.remove = lantiq_ssc_remove,
+	.driver = {
+		.name = "spi-lantiq-ssc",
+		.owner = THIS_MODULE,
+		.of_match_table = lantiq_ssc_match,
+	},
+};
+module_platform_driver(lantiq_ssc_driver);
+
+MODULE_DESCRIPTION("Lantiq SSC SPI controller driver");
+MODULE_AUTHOR("Daniel Schwierzeck <daniel.schwierzeck@xxxxxxxxx>");
+MODULE_AUTHOR("Hauke Mehrtens <hauke@xxxxxxxxxx>");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:spi-lantiq-ssc");
-- 
2.10.2

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