drivers: spi: add spi support for QCA/Atheros ath79 SOCs

This patch add a compatible spi driver for ath79 series SOC.

Signed-off-by: Wills Wang <wills.wang@live.com>
Reviewed-by: Thomas Chou <thomas@wytron.com.tw>
Reviewed-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>

3 files changed, 250 insertions, 0 deletions

diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index f0258f8..b7fd8e5 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -23,6 +23,15 @@ config ALTERA_SPI
 	  IP core. Please find details on the "Embedded Peripherals IP
 	  User Guide" of Altera.
 
+config ATH79_SPI
+	bool "Atheros SPI driver"
+	depends on ARCH_ATH79
+	help
+	  Enable the Atheros ar7xxx/ar9xxx SoC SPI driver, it was used
+	  to access SPI NOR flash and other SPI peripherals. This driver
+	  uses driver model and requires a device tree binding to operate.
+	  please refer to doc/device-tree-bindings/spi/spi-ath79.txt.
+
 config CADENCE_QSPI
 	bool "Cadence QSPI driver"
 	help
diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
index 3eca745..7fb2926 100644
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -17,6 +17,7 @@ endif
 
 obj-$(CONFIG_ALTERA_SPI) += altera_spi.o
 obj-$(CONFIG_ARMADA100_SPI) += armada100_spi.o
+obj-$(CONFIG_ATH79_SPI) += ath79_spi.o
 obj-$(CONFIG_ATMEL_DATAFLASH_SPI) += atmel_dataflash_spi.o
 obj-$(CONFIG_ATMEL_SPI) += atmel_spi.o
 obj-$(CONFIG_BFIN_SPI) += bfin_spi.o
diff --git a/drivers/spi/ath79_spi.c b/drivers/spi/ath79_spi.c
new file mode 100644
index 0000000..0c1022d
--- /dev/null
+++ b/drivers/spi/ath79_spi.c
@@ -0,0 +1,240 @@
+/*
+ * Copyright (C) 2015-2016 Wills Wang <wills.wang@live.com>
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ */
+
+#include <common.h>
+#include <spi.h>
+#include <dm.h>
+#include <div64.h>
+#include <errno.h>
+#include <asm/io.h>
+#include <asm/addrspace.h>
+#include <asm/types.h>
+#include <dm/pinctrl.h>
+#include <mach/ar71xx_regs.h>
+
+/* CLOCK_DIVIDER = 3 (SPI clock = 200 / 8 ~ 25 MHz) */
+#define ATH79_SPI_CLK_DIV(x)           (((x) >> 1) - 1)
+#define ATH79_SPI_RRW_DELAY_FACTOR     12000
+#define ATH79_SPI_MHZ                  (1000 * 1000)
+
+struct ath79_spi_priv {
+	void __iomem *regs;
+	u32 rrw_delay;
+};
+
+static void spi_cs_activate(struct udevice *dev)
+{
+	struct udevice *bus = dev_get_parent(dev);
+	struct ath79_spi_priv *priv = dev_get_priv(bus);
+
+	writel(AR71XX_SPI_FS_GPIO, priv->regs + AR71XX_SPI_REG_FS);
+	writel(AR71XX_SPI_IOC_CS_ALL, priv->regs + AR71XX_SPI_REG_IOC);
+}
+
+static void spi_cs_deactivate(struct udevice *dev)
+{
+	struct udevice *bus = dev_get_parent(dev);
+	struct ath79_spi_priv *priv = dev_get_priv(bus);
+
+	writel(AR71XX_SPI_IOC_CS_ALL, priv->regs + AR71XX_SPI_REG_IOC);
+	writel(0, priv->regs + AR71XX_SPI_REG_FS);
+}
+
+static int ath79_spi_claim_bus(struct udevice *dev)
+{
+	return 0;
+}
+
+static int ath79_spi_release_bus(struct udevice *dev)
+{
+	return 0;
+}
+
+static int ath79_spi_xfer(struct udevice *dev, unsigned int bitlen,
+		const void *dout, void *din, unsigned long flags)
+{
+	struct udevice *bus = dev_get_parent(dev);
+	struct ath79_spi_priv *priv = dev_get_priv(bus);
+	struct dm_spi_slave_platdata *slave = dev_get_parent_platdata(dev);
+	u8 *rx = din;
+	const u8 *tx = dout;
+	u8 curbyte, curbitlen, restbits;
+	u32 bytes = bitlen / 8;
+	u32 out, in;
+	u64 tick;
+
+	if (flags & SPI_XFER_BEGIN)
+		spi_cs_activate(dev);
+
+	restbits = (bitlen % 8);
+	if (restbits)
+		bytes++;
+
+	out = AR71XX_SPI_IOC_CS_ALL & ~(AR71XX_SPI_IOC_CS(slave->cs));
+	while (bytes > 0) {
+		bytes--;
+		curbyte = 0;
+		if (tx)
+			curbyte = *tx++;
+
+		if (restbits && !bytes) {
+			curbitlen = restbits;
+			curbyte <<= 8 - restbits;
+		} else {
+			curbitlen = 8;
+		}
+
+		for (curbyte <<= (8 - curbitlen); curbitlen; curbitlen--) {
+			if (curbyte & 0x80)
+				out |= AR71XX_SPI_IOC_DO;
+			else
+				out &= ~(AR71XX_SPI_IOC_DO);
+
+			writel(out, priv->regs + AR71XX_SPI_REG_IOC);
+
+			/* delay for low level */
+			if (priv->rrw_delay) {
+				tick = get_ticks() + priv->rrw_delay;
+				while (get_ticks() < tick)
+					/*NOP*/;
+			}
+
+			writel(out | AR71XX_SPI_IOC_CLK,
+			       priv->regs + AR71XX_SPI_REG_IOC);
+
+			/* delay for high level */
+			if (priv->rrw_delay) {
+				tick = get_ticks() + priv->rrw_delay;
+				while (get_ticks() < tick)
+					/*NOP*/;
+			}
+
+			curbyte <<= 1;
+		}
+
+		if (!bytes)
+			writel(out, priv->regs + AR71XX_SPI_REG_IOC);
+
+		in = readl(priv->regs + AR71XX_SPI_REG_RDS);
+		if (rx) {
+			if (restbits && !bytes)
+				*rx++ = (in << (8 - restbits));
+			else
+				*rx++ = in;
+		}
+	}
+
+	if (flags & SPI_XFER_END)
+		spi_cs_deactivate(dev);
+
+	return 0;
+}
+
+
+static int ath79_spi_set_speed(struct udevice *bus, uint speed)
+{
+	struct ath79_spi_priv *priv = dev_get_priv(bus);
+	u32 val, div = 0;
+	u64 time;
+
+	if (speed)
+		div = get_bus_freq(0) / speed;
+
+	if (div > 63)
+		div = 63;
+
+	if (div < 5)
+		div = 5;
+
+	/* calculate delay */
+	time = get_tbclk();
+	do_div(time, speed / 2);
+	val = get_bus_freq(0) / ATH79_SPI_MHZ;
+	val = ATH79_SPI_RRW_DELAY_FACTOR / val;
+	if (time > val)
+		priv->rrw_delay = time - val + 1;
+	else
+		priv->rrw_delay = 0;
+
+	writel(AR71XX_SPI_FS_GPIO, priv->regs + AR71XX_SPI_REG_FS);
+	clrsetbits_be32(priv->regs + AR71XX_SPI_REG_CTRL,
+			AR71XX_SPI_CTRL_DIV_MASK,
+			ATH79_SPI_CLK_DIV(div));
+	writel(0, priv->regs + AR71XX_SPI_REG_FS);
+	return 0;
+}
+
+static int ath79_spi_set_mode(struct udevice *bus, uint mode)
+{
+	return 0;
+}
+
+static int ath79_spi_probe(struct udevice *bus)
+{
+	struct ath79_spi_priv *priv = dev_get_priv(bus);
+	struct udevice *pinctrl;
+	fdt_addr_t addr;
+	int ret;
+
+	ret = uclass_get_device(UCLASS_PINCTRL, 0, &pinctrl);
+	if (ret)
+		return ret;
+	ret = pinctrl_get_periph_id(pinctrl, bus);
+	if (ret < 0)
+		return ret;
+	ret = pinctrl_request(pinctrl, ret, 0);
+	if (ret < 0)
+		return ret;
+
+	addr = dev_get_addr(bus);
+	if (addr == FDT_ADDR_T_NONE)
+		return -EINVAL;
+
+	priv->regs = map_physmem(addr,
+				 AR71XX_SPI_SIZE,
+				 MAP_NOCACHE);
+
+	/* Init SPI Hardware, disable remap, set clock */
+	writel(AR71XX_SPI_FS_GPIO, priv->regs + AR71XX_SPI_REG_FS);
+	writel(AR71XX_SPI_CTRL_RD | ATH79_SPI_CLK_DIV(8),
+	       priv->regs + AR71XX_SPI_REG_CTRL);
+	writel(0, priv->regs + AR71XX_SPI_REG_FS);
+
+	return 0;
+}
+
+static int ath79_cs_info(struct udevice *bus, uint cs,
+			   struct spi_cs_info *info)
+{
+	/* Always allow activity on CS 0/1/2 */
+	if (cs >= 3)
+		return -ENODEV;
+
+	return 0;
+}
+
+static const struct dm_spi_ops ath79_spi_ops = {
+	.claim_bus  = ath79_spi_claim_bus,
+	.release_bus    = ath79_spi_release_bus,
+	.xfer       = ath79_spi_xfer,
+	.set_speed  = ath79_spi_set_speed,
+	.set_mode   = ath79_spi_set_mode,
+	.cs_info    = ath79_cs_info,
+};
+
+static const struct udevice_id ath79_spi_ids[] = {
+	{ .compatible = "qca,ar7100-spi" },
+	{}
+};
+
+U_BOOT_DRIVER(ath79_spi) = {
+	.name   = "ath79_spi",
+	.id = UCLASS_SPI,
+	.of_match = ath79_spi_ids,
+	.ops    = &ath79_spi_ops,
+	.priv_auto_alloc_size = sizeof(struct ath79_spi_priv),
+	.probe  = ath79_spi_probe,
+};