spi: Add designware master SPI DM driver used on SoCFPGA

This patch adds the driver for the Designware master SPI controller. This
IP core is integrated on the Altera SoCFPGA. This implementation is a
driver model (DM) implementation. So multiple SPI drivers can be used.
Thats necessary, since SoCFPGA also integrates the Cadence QSPI controller
used to connect the SPI NOR flashes. Without DM, using multiple SPI
drivers is not possible.

This driver is very loosely based on the Linux driver. Most of the Linux
driver is removed. Only the polling loop for the transfer is really used
from this driver, as we don't support interrupts and DMA right now.

This is tested on the SoCrates SoCFPGA board using the SPI pins on the
P14 header.

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Chin Liang See <clsee@altera.com>
Cc: Dinh Nguyen <dinguyen@altera.com>
Cc: Vince Bridgers <vbridger@altera.com>
Cc: Marek Vasut <marex@denx.de>
Cc: Pavel Machek <pavel@denx.de>
Reviewed-by: Simon Glass <sjg@chromium.org>
Cc: Jagannadha Sutradharudu Teki <jagannadh.teki@gmail.com>

2 files changed, 426 insertions, 0 deletions

diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
index 964fdc1..edbd520 100644
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -27,6 +27,7 @@ obj-$(CONFIG_CADENCE_QSPI) += cadence_qspi.o cadence_qspi_apb.o
 obj-$(CONFIG_CF_SPI) += cf_spi.o
 obj-$(CONFIG_CF_QSPI) += cf_qspi.o
 obj-$(CONFIG_DAVINCI_SPI) += davinci_spi.o
+obj-$(CONFIG_DESIGNWARE_SPI) += designware_spi.o
 obj-$(CONFIG_EXYNOS_SPI) += exynos_spi.o
 obj-$(CONFIG_FTSSP010_SPI) += ftssp010_spi.o
 obj-$(CONFIG_ICH_SPI) +=  ich.o
diff --git a/drivers/spi/designware_spi.c b/drivers/spi/designware_spi.c
new file mode 100644
index 0000000..1bc0d04
--- /dev/null
+++ b/drivers/spi/designware_spi.c
@@ -0,0 +1,425 @@
+/*
+ * Designware master SPI core controller driver
+ *
+ * Copyright (C) 2014 Stefan Roese <sr@denx.de>
+ *
+ * Very loosly based on the Linux driver version which is:
+ * Copyright (c) 2009, Intel Corporation.
+ *
+ * SPDX-License-Identifier:	GPL-2.0
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <errno.h>
+#include <malloc.h>
+#include <spi.h>
+#include <fdtdec.h>
+#include <linux/compat.h>
+#include <asm/io.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+/* Register offsets */
+#define DW_SPI_CTRL0			0x00
+#define DW_SPI_CTRL1			0x04
+#define DW_SPI_SSIENR			0x08
+#define DW_SPI_MWCR			0x0c
+#define DW_SPI_SER			0x10
+#define DW_SPI_BAUDR			0x14
+#define DW_SPI_TXFLTR			0x18
+#define DW_SPI_RXFLTR			0x1c
+#define DW_SPI_TXFLR			0x20
+#define DW_SPI_RXFLR			0x24
+#define DW_SPI_SR			0x28
+#define DW_SPI_IMR			0x2c
+#define DW_SPI_ISR			0x30
+#define DW_SPI_RISR			0x34
+#define DW_SPI_TXOICR			0x38
+#define DW_SPI_RXOICR			0x3c
+#define DW_SPI_RXUICR			0x40
+#define DW_SPI_MSTICR			0x44
+#define DW_SPI_ICR			0x48
+#define DW_SPI_DMACR			0x4c
+#define DW_SPI_DMATDLR			0x50
+#define DW_SPI_DMARDLR			0x54
+#define DW_SPI_IDR			0x58
+#define DW_SPI_VERSION			0x5c
+#define DW_SPI_DR			0x60
+
+/* Bit fields in CTRLR0 */
+#define SPI_DFS_OFFSET			0
+
+#define SPI_FRF_OFFSET			4
+#define SPI_FRF_SPI			0x0
+#define SPI_FRF_SSP			0x1
+#define SPI_FRF_MICROWIRE		0x2
+#define SPI_FRF_RESV			0x3
+
+#define SPI_MODE_OFFSET			6
+#define SPI_SCPH_OFFSET			6
+#define SPI_SCOL_OFFSET			7
+
+#define SPI_TMOD_OFFSET			8
+#define SPI_TMOD_MASK			(0x3 << SPI_TMOD_OFFSET)
+#define	SPI_TMOD_TR			0x0		/* xmit & recv */
+#define SPI_TMOD_TO			0x1		/* xmit only */
+#define SPI_TMOD_RO			0x2		/* recv only */
+#define SPI_TMOD_EPROMREAD		0x3		/* eeprom read mode */
+
+#define SPI_SLVOE_OFFSET		10
+#define SPI_SRL_OFFSET			11
+#define SPI_CFS_OFFSET			12
+
+/* Bit fields in SR, 7 bits */
+#define SR_MASK				0x7f		/* cover 7 bits */
+#define SR_BUSY				(1 << 0)
+#define SR_TF_NOT_FULL			(1 << 1)
+#define SR_TF_EMPT			(1 << 2)
+#define SR_RF_NOT_EMPT			(1 << 3)
+#define SR_RF_FULL			(1 << 4)
+#define SR_TX_ERR			(1 << 5)
+#define SR_DCOL				(1 << 6)
+
+#define RX_TIMEOUT			1000
+
+struct dw_spi_platdata {
+	s32 frequency;		/* Default clock frequency, -1 for none */
+	void __iomem *regs;
+};
+
+struct dw_spi_priv {
+	void __iomem *regs;
+	unsigned int freq;		/* Default frequency */
+	unsigned int mode;
+
+	int bits_per_word;
+	u8 cs;			/* chip select pin */
+	u8 n_bytes;		/* current is a 1/2/4 byte op */
+	u8 tmode;		/* TR/TO/RO/EEPROM */
+	u8 type;		/* SPI/SSP/MicroWire */
+	int len;
+
+	u32 fifo_len;		/* depth of the FIFO buffer */
+	void *tx;
+	void *tx_end;
+	void *rx;
+	void *rx_end;
+};
+
+static inline u32 dw_readl(struct dw_spi_priv *priv, u32 offset)
+{
+	return __raw_readl(priv->regs + offset);
+}
+
+static inline void dw_writel(struct dw_spi_priv *priv, u32 offset, u32 val)
+{
+	__raw_writel(val, priv->regs + offset);
+}
+
+static inline u16 dw_readw(struct dw_spi_priv *priv, u32 offset)
+{
+	return __raw_readw(priv->regs + offset);
+}
+
+static inline void dw_writew(struct dw_spi_priv *priv, u32 offset, u16 val)
+{
+	__raw_writew(val, priv->regs + offset);
+}
+
+static int dw_spi_ofdata_to_platdata(struct udevice *bus)
+{
+	struct dw_spi_platdata *plat = bus->platdata;
+	const void *blob = gd->fdt_blob;
+	int node = bus->of_offset;
+
+	plat->regs = (struct dw_spi *)fdtdec_get_addr(blob, node, "reg");
+
+	/* Use 500KHz as a suitable default */
+	plat->frequency = fdtdec_get_int(blob, node, "spi-max-frequency",
+					500000);
+	debug("%s: regs=%p max-frequency=%d\n", __func__, plat->regs,
+	      plat->frequency);
+
+	return 0;
+}
+
+static inline void spi_enable_chip(struct dw_spi_priv *priv, int enable)
+{
+	dw_writel(priv, DW_SPI_SSIENR, (enable ? 1 : 0));
+}
+
+/* Restart the controller, disable all interrupts, clean rx fifo */
+static void spi_hw_init(struct dw_spi_priv *priv)
+{
+	spi_enable_chip(priv, 0);
+	dw_writel(priv, DW_SPI_IMR, 0xff);
+	spi_enable_chip(priv, 1);
+
+	/*
+	 * Try to detect the FIFO depth if not set by interface driver,
+	 * the depth could be from 2 to 256 from HW spec
+	 */
+	if (!priv->fifo_len) {
+		u32 fifo;
+
+		for (fifo = 2; fifo <= 257; fifo++) {
+			dw_writew(priv, DW_SPI_TXFLTR, fifo);
+			if (fifo != dw_readw(priv, DW_SPI_TXFLTR))
+				break;
+		}
+
+		priv->fifo_len = (fifo == 257) ? 0 : fifo;
+		dw_writew(priv, DW_SPI_TXFLTR, 0);
+	}
+	debug("%s: fifo_len=%d\n", __func__, priv->fifo_len);
+}
+
+static int dw_spi_probe(struct udevice *bus)
+{
+	struct dw_spi_platdata *plat = dev_get_platdata(bus);
+	struct dw_spi_priv *priv = dev_get_priv(bus);
+
+	priv->regs = plat->regs;
+	priv->freq = plat->frequency;
+
+	/* Currently only bits_per_word == 8 supported */
+	priv->bits_per_word = 8;
+	priv->n_bytes = 1;
+
+	priv->tmode = 0; /* Tx & Rx */
+
+	/* Basic HW init */
+	spi_hw_init(priv);
+
+	return 0;
+}
+
+/* Return the max entries we can fill into tx fifo */
+static inline u32 tx_max(struct dw_spi_priv *priv)
+{
+	u32 tx_left, tx_room, rxtx_gap;
+
+	tx_left = (priv->tx_end - priv->tx) / priv->n_bytes;
+	tx_room = priv->fifo_len - dw_readw(priv, DW_SPI_TXFLR);
+
+	/*
+	 * Another concern is about the tx/rx mismatch, we
+	 * though to use (priv->fifo_len - rxflr - txflr) as
+	 * one maximum value for tx, but it doesn't cover the
+	 * data which is out of tx/rx fifo and inside the
+	 * shift registers. So a control from sw point of
+	 * view is taken.
+	 */
+	rxtx_gap = ((priv->rx_end - priv->rx) - (priv->tx_end - priv->tx)) /
+		priv->n_bytes;
+
+	return min3(tx_left, tx_room, (u32)(priv->fifo_len - rxtx_gap));
+}
+
+/* Return the max entries we should read out of rx fifo */
+static inline u32 rx_max(struct dw_spi_priv *priv)
+{
+	u32 rx_left = (priv->rx_end - priv->rx) / priv->n_bytes;
+
+	return min_t(u32, rx_left, dw_readw(priv, DW_SPI_RXFLR));
+}
+
+static void dw_writer(struct dw_spi_priv *priv)
+{
+	u32 max = tx_max(priv);
+	u16 txw = 0;
+
+	while (max--) {
+		/* Set the tx word if the transfer's original "tx" is not null */
+		if (priv->tx_end - priv->len) {
+			if (priv->n_bytes == 1)
+				txw = *(u8 *)(priv->tx);
+			else
+				txw = *(u16 *)(priv->tx);
+		}
+		dw_writew(priv, DW_SPI_DR, txw);
+		debug("%s: tx=0x%02x\n", __func__, txw);
+		priv->tx += priv->n_bytes;
+	}
+}
+
+static int dw_reader(struct dw_spi_priv *priv)
+{
+	unsigned start = get_timer(0);
+	u32 max;
+	u16 rxw;
+
+	/* Wait for rx data to be ready */
+	while (rx_max(priv) == 0) {
+		if (get_timer(start) > RX_TIMEOUT)
+			return -ETIMEDOUT;
+	}
+
+	max = rx_max(priv);
+
+	while (max--) {
+		rxw = dw_readw(priv, DW_SPI_DR);
+		debug("%s: rx=0x%02x\n", __func__, rxw);
+		/* Care rx only if the transfer's original "rx" is not null */
+		if (priv->rx_end - priv->len) {
+			if (priv->n_bytes == 1)
+				*(u8 *)(priv->rx) = rxw;
+			else
+				*(u16 *)(priv->rx) = rxw;
+		}
+		priv->rx += priv->n_bytes;
+	}
+
+	return 0;
+}
+
+static int poll_transfer(struct dw_spi_priv *priv)
+{
+	int ret;
+
+	do {
+		dw_writer(priv);
+		ret = dw_reader(priv);
+		if (ret < 0)
+			return ret;
+	} while (priv->rx_end > priv->rx);
+
+	return 0;
+}
+
+static int dw_spi_xfer(struct udevice *dev, unsigned int bitlen,
+		       const void *dout, void *din, unsigned long flags)
+{
+	struct udevice *bus = dev->parent;
+	struct dw_spi_priv *priv = dev_get_priv(bus);
+	const u8 *tx = dout;
+	u8 *rx = din;
+	int ret = 0;
+	u32 cr0 = 0;
+	u8 bits = 0;
+	u32 cs;
+
+	/* spi core configured to do 8 bit transfers */
+	if (bitlen % 8) {
+		debug("Non byte aligned SPI transfer.\n");
+		return -1;
+	}
+
+	bits = priv->bits_per_word;
+	priv->n_bytes = bits >> 3;
+	cr0 = (bits - 1) | (priv->type << SPI_FRF_OFFSET) |
+		(priv->mode << SPI_MODE_OFFSET) |
+		(priv->tmode << SPI_TMOD_OFFSET);
+
+	if (rx && tx)
+		priv->tmode = SPI_TMOD_TR;
+	else if (rx)
+		priv->tmode = SPI_TMOD_RO;
+	else
+		priv->tmode = SPI_TMOD_TO;
+
+	cr0 &= ~SPI_TMOD_MASK;
+	cr0 |= (priv->tmode << SPI_TMOD_OFFSET);
+
+	priv->len = bitlen / 8;
+	debug("%s: rx=%p tx=%p len=%d [bytes]\n", __func__, rx, tx, priv->len);
+
+	priv->tx = (void *)tx;
+	priv->tx_end = priv->tx + priv->len;
+	priv->rx = rx;
+	priv->rx_end = priv->rx + priv->len;
+
+	/* Disable controller before writing control registers */
+	spi_enable_chip(priv, 0);
+
+	debug("%s: cr0=%08x\n", __func__, cr0);
+	/* Reprogram cr0 only if changed */
+	if (dw_readw(priv, DW_SPI_CTRL0) != cr0)
+		dw_writew(priv, DW_SPI_CTRL0, cr0);
+
+	/*
+	 * Configure the desired SS (slave select 0...3) in the controller
+	 * The DW SPI controller will activate and deactivate this CS
+	 * automatically. So no cs_activate() etc is needed in this driver.
+	 */
+	cs = spi_chip_select(dev);
+	dw_writel(priv, DW_SPI_SER, 1 << cs);
+
+	/* Enable controller after writing control registers */
+	spi_enable_chip(priv, 1);
+
+	/* Start transfer in a polling loop */
+	ret = poll_transfer(priv);
+
+	return ret;
+}
+
+static int dw_spi_set_speed(struct udevice *bus, uint speed)
+{
+	struct dw_spi_platdata *plat = bus->platdata;
+	struct dw_spi_priv *priv = dev_get_priv(bus);
+	u16 clk_div;
+
+	if (speed > plat->frequency)
+		speed = plat->frequency;
+
+	/* Disable controller before writing control registers */
+	spi_enable_chip(priv, 0);
+
+	/* clk_div doesn't support odd number */
+	clk_div = CONFIG_DW_SPI_REF_CLK / speed;
+	clk_div = (clk_div + 1) & 0xfffe;
+	dw_writel(priv, DW_SPI_BAUDR, clk_div);
+
+	/* Enable controller after writing control registers */
+	spi_enable_chip(priv, 1);
+
+	priv->freq = speed;
+	debug("%s: regs=%p speed=%d clk_div=%d\n", __func__, priv->regs,
+	      priv->freq, clk_div);
+
+	return 0;
+}
+
+static int dw_spi_set_mode(struct udevice *bus, uint mode)
+{
+	struct dw_spi_priv *priv = dev_get_priv(bus);
+
+	/*
+	 * Can't set mode yet. Since this depends on if rx, tx, or
+	 * rx & tx is requested. So we have to defer this to the
+	 * real transfer function.
+	 */
+	priv->mode = mode;
+	debug("%s: regs=%p, mode=%d\n", __func__, priv->regs, priv->mode);
+
+	return 0;
+}
+
+static const struct dm_spi_ops dw_spi_ops = {
+	.xfer		= dw_spi_xfer,
+	.set_speed	= dw_spi_set_speed,
+	.set_mode	= dw_spi_set_mode,
+	/*
+	 * cs_info is not needed, since we require all chip selects to be
+	 * in the device tree explicitly
+	 */
+};
+
+static const struct udevice_id dw_spi_ids[] = {
+	{ .compatible = "snps,dw-spi-mmio" },
+	{ }
+};
+
+U_BOOT_DRIVER(dw_spi) = {
+	.name = "dw_spi",
+	.id = UCLASS_SPI,
+	.of_match = dw_spi_ids,
+	.ops = &dw_spi_ops,
+	.ofdata_to_platdata = dw_spi_ofdata_to_platdata,
+	.platdata_auto_alloc_size = sizeof(struct dw_spi_platdata),
+	.priv_auto_alloc_size = sizeof(struct dw_spi_priv),
+	.per_child_auto_alloc_size = sizeof(struct spi_slave),
+	.probe = dw_spi_probe,
+};