[PATCH v2 2/5] spi: add controller driver for Atheros AR7XXX/AR9XXX SoCs

[Antony Pavlov <antonynpavlov@gmail.com>]

Signed-off-by: Antony Pavlov <antonynpavlov@gmail.com>
---
 drivers/spi/Kconfig     |   4 +
 drivers/spi/Makefile    |   1 +
 drivers/spi/ath79_spi.c | 299 ++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 304 insertions(+)

diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index 422693c..60eaaaa 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -10,6 +10,10 @@ config DRIVER_SPI_ALTERA
 	bool "Altera SPI Master driver"
 	depends on NIOS2
 
+config DRIVER_SPI_ATH79
+	bool "Atheros AR71XX/AR724X/AR913X/AR933X SPI controller driver"
+	depends on MACH_MIPS_ATH79
+
 config DRIVER_SPI_ATMEL
 	bool "Atmel (AT91) SPI Master driver"
 	depends on ARCH_AT91
diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
index 1036f8f..7469479 100644
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -1,4 +1,5 @@
 obj-$(CONFIG_SPI) += spi.o
+obj-$(CONFIG_DRIVER_SPI_ATH79) += ath79_spi.o
 obj-$(CONFIG_DRIVER_SPI_IMX) += imx_spi.o
 obj-$(CONFIG_DRIVER_SPI_MVEBU) += mvebu_spi.o
 obj-$(CONFIG_DRIVER_SPI_MXS) += mxs_spi.o
diff --git a/drivers/spi/ath79_spi.c b/drivers/spi/ath79_spi.c
new file mode 100644
index 0000000..d9ab269
--- /dev/null
+++ b/drivers/spi/ath79_spi.c
@@ -0,0 +1,299 @@
+/*
+ * Copyright (C) 2013, 2014 Antony Pavlov <antonynpavlov@gmail.com>
+ *
+ * This file is part of barebox.
+ * See file CREDITS for list of people who contributed to this project.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#include <common.h>
+#include <init.h>
+#include <driver.h>
+#include <spi/spi.h>
+#include <io.h>
+#include <clock.h>
+
+struct ath79_spi {
+	struct spi_master	master;
+	void __iomem		*regs;
+	u32			val;
+	u32			reg_ctrl;
+};
+
+#define AR71XX_SPI_REG_FS	0x00	/* Function Select */
+#define AR71XX_SPI_REG_CTRL	0x04	/* SPI Control */
+#define AR71XX_SPI_REG_IOC	0x08	/* SPI I/O Control */
+#define AR71XX_SPI_REG_RDS	0x0c	/* Read Data Shift */
+
+#define AR71XX_SPI_FS_GPIO	BIT(0)	/* Enable GPIO mode */
+
+#define AR71XX_SPI_IOC_DO	BIT(0)	/* Data Out pin */
+#define AR71XX_SPI_IOC_CLK	BIT(8)	/* CLK pin */
+#define AR71XX_SPI_IOC_CS(n)	BIT(16 + (n))
+#define AR71XX_SPI_IOC_CS0	AR71XX_SPI_IOC_CS(0)
+#define AR71XX_SPI_IOC_CS1	AR71XX_SPI_IOC_CS(1)
+#define AR71XX_SPI_IOC_CS2	AR71XX_SPI_IOC_CS(2)
+#define AR71XX_SPI_IOC_CS_ALL	(AR71XX_SPI_IOC_CS0 | AR71XX_SPI_IOC_CS1 | \
+				 AR71XX_SPI_IOC_CS2)
+
+static inline u32 ath79_spi_rr(struct ath79_spi *sp, int reg)
+{
+	return cpu_readl(sp->regs + reg);
+}
+
+static inline void ath79_spi_wr(struct ath79_spi *sp, u32 val, int reg)
+{
+	cpu_writel(val, sp->regs + reg);
+}
+
+static inline void setbits(struct ath79_spi *sp, int bits, int on)
+{
+	/*
+	 * We are the only user of SCSPTR so no locking is required.
+	 * Reading bit 2 and 0 in SCSPTR gives pin state as input.
+	 * Writing the same bits sets the output value.
+	 * This makes regular read-modify-write difficult so we
+	 * use sp->val to keep track of the latest register value.
+	 */
+
+	if (on)
+		sp->val |= bits;
+	else
+		sp->val &= ~bits;
+
+	ath79_spi_wr(sp, sp->val, AR71XX_SPI_REG_IOC);
+}
+
+static inline struct ath79_spi *ath79_spidev_to_sp(struct spi_device *spi)
+{
+	return container_of(spi->master, struct ath79_spi, master);
+}
+
+static inline void setsck(struct spi_device *spi, int on)
+{
+	struct ath79_spi *sc = ath79_spidev_to_sp(spi);
+
+	setbits(sc, AR71XX_SPI_IOC_CLK, on);
+}
+
+static inline void setmosi(struct spi_device *spi, int on)
+{
+	struct ath79_spi *sc = ath79_spidev_to_sp(spi);
+
+	setbits(sc, AR71XX_SPI_IOC_DO, on);
+}
+
+static inline u32 getmiso(struct spi_device *spi)
+{
+	struct ath79_spi *sc = ath79_spidev_to_sp(spi);
+
+	return !!((ath79_spi_rr(sc, AR71XX_SPI_REG_RDS) & 1));
+}
+
+#include "spi-bitbang-txrx.h"
+
+static inline void ath79_spi_chipselect(struct ath79_spi *sp, int chipselect)
+{
+	int off_bits;
+
+	off_bits = 0xffffffff;
+
+	switch (chipselect) {
+	case 0:
+		off_bits &= ~AR71XX_SPI_IOC_CS0;
+		break;
+
+	case 1:
+		off_bits &= ~AR71XX_SPI_IOC_CS1;
+		break;
+
+	case 2:
+		off_bits &= ~AR71XX_SPI_IOC_CS2;
+		break;
+
+	case 3:
+		break;
+	}
+
+	/* by default inactivate chip selects */
+	sp->val |= AR71XX_SPI_IOC_CS_ALL;
+	sp->val &= off_bits;
+
+	ath79_spi_wr(sp, sp->val, AR71XX_SPI_REG_IOC);
+}
+
+static int ath79_spi_setup(struct spi_device *spi)
+{
+	struct spi_master *master = spi->master;
+	struct device_d spi_dev = spi->dev;
+
+	if (spi->bits_per_word != 8) {
+		dev_err(master->dev, "master doesn't support %d bits per word requested by %s\n",
+			spi->bits_per_word, spi_dev.name);
+		return -EINVAL;
+	}
+
+	if ((spi->mode & (SPI_CPHA | SPI_CPOL)) != SPI_MODE_0) {
+		dev_err(master->dev, "master doesn't support SPI_MODE%d requested by %s\n",
+			spi->mode & (SPI_CPHA | SPI_CPOL), spi_dev.name);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int ath79_spi_read(struct spi_device *spi, void *buf, size_t nbyte)
+{
+	ssize_t cnt = 0;
+	u8 *rxf_buf = buf;
+
+	while (cnt < nbyte) {
+		*rxf_buf = bitbang_txrx_be_cpha1(spi, 1000, 1, 0, 8);
+		rxf_buf++;
+		cnt++;
+	}
+
+	return cnt;
+}
+
+static int ath79_spi_write(struct spi_device *spi,
+				const void *buf, size_t nbyte)
+{
+	ssize_t cnt = 0;
+	const u8 *txf_buf = buf;
+
+	while (cnt < nbyte) {
+		bitbang_txrx_be_cpha1(spi, 1000, 1, (u32)*txf_buf, 8);
+		txf_buf++;
+		cnt++;
+	}
+
+	return 0;
+}
+
+static int ath79_spi_transfer(struct spi_device *spi, struct spi_message *mesg)
+{
+	struct ath79_spi *sc = ath79_spidev_to_sp(spi);
+	struct spi_transfer *t;
+
+	mesg->actual_length = 0;
+
+	/* activate chip select signal */
+	ath79_spi_chipselect(sc, spi->chip_select);
+
+	list_for_each_entry(t, &mesg->transfers, transfer_list) {
+
+		if (t->tx_buf)
+			ath79_spi_write(spi, t->tx_buf, t->len);
+
+		if (t->rx_buf)
+			ath79_spi_read(spi, t->rx_buf, t->len);
+
+		mesg->actual_length += t->len;
+	}
+
+	/* inactivate chip select signal */
+	ath79_spi_chipselect(sc, -1);
+
+	return 0;
+}
+
+static void ath79_spi_enable(struct ath79_spi *sp)
+{
+	/* enable GPIO mode */
+	ath79_spi_wr(sp, AR71XX_SPI_FS_GPIO, AR71XX_SPI_REG_FS);
+
+	/* save CTRL register */
+	sp->reg_ctrl = ath79_spi_rr(sp, AR71XX_SPI_REG_CTRL);
+	sp->val = ath79_spi_rr(sp, AR71XX_SPI_REG_IOC);
+
+	/* TODO: setup speed? */
+	ath79_spi_wr(sp, 0x43, AR71XX_SPI_REG_CTRL);
+}
+
+static void ath79_spi_disable(struct ath79_spi *sp)
+{
+	/* restore CTRL register */
+	ath79_spi_wr(sp, sp->reg_ctrl, AR71XX_SPI_REG_CTRL);
+	/* disable GPIO mode */
+	ath79_spi_wr(sp, 0, AR71XX_SPI_REG_FS);
+}
+
+static int ath79_spi_probe(struct device_d *dev)
+{
+	struct spi_master *master;
+	struct ath79_spi *ath79_spi;
+
+	ath79_spi = xzalloc(sizeof(*ath79_spi));
+	dev->priv = ath79_spi;
+
+	master = &ath79_spi->master;
+	master->dev = dev;
+
+	master->bus_num = dev->id;
+	master->setup = ath79_spi_setup;
+	master->transfer = ath79_spi_transfer;
+	master->num_chipselect = 3;
+
+	if (IS_ENABLED(CONFIG_OFDEVICE)) {
+		struct device_node *node = dev->device_node;
+		u32 num_cs;
+		int ret;
+
+		ret = of_property_read_u32(node, "num-chipselects", &num_cs);
+		if (ret)
+			num_cs = 3;
+
+		if (num_cs > 3) {
+			dev_err(dev, "master doesn't support num-chipselects > 3\n");
+		}
+
+		master->num_chipselect = num_cs;
+	}
+
+	ath79_spi->regs = dev_request_mem_region(dev, 0);
+
+	/* enable gpio mode */
+	ath79_spi_enable(ath79_spi);
+
+	/* inactivate chip select signal */
+	ath79_spi_chipselect(ath79_spi, -1);
+
+	spi_register_master(master);
+
+	return 0;
+}
+
+static void ath79_spi_remove(struct device_d *dev)
+{
+	struct ath79_spi *sp = dev->priv;
+
+	ath79_spi_disable(sp);
+}
+
+static __maybe_unused struct of_device_id ath79_spi_dt_ids[] = {
+	{
+		.compatible = "qca,ath79-spi",
+	},
+	{
+		/* sentinel */
+	}
+};
+
+static struct driver_d ath79_spi_driver = {
+	.name  = "ath79-spi",
+	.probe = ath79_spi_probe,
+	.remove = ath79_spi_remove,
+	.of_compatible = DRV_OF_COMPAT(ath79_spi_dt_ids),
+};
+device_platform_driver(ath79_spi_driver);
-- 
1.9.0


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