add SPI controller driver for the PB44 board

SVN-Revision: 16781

1 files changed, 299 insertions, 0 deletions

diff --git a/target/linux/ar71xx/files/drivers/spi/pb44_spi.c b/target/linux/ar71xx/files/drivers/spi/pb44_spi.c
new file mode 100644
index 0000000000..32e6ea6426
--- /dev/null
+++ b/target/linux/ar71xx/files/drivers/spi/pb44_spi.c
@@ -0,0 +1,299 @@
+/*
+ * Atheros PB44 board SPI controller driver
+ *
+ * Copyright (C) 2009 Gabor Juhos <juhosg@openwrt.org>
+ *
+ * This program is free software; you can redistribute 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/init.h>
+#include <linux/delay.h>
+#include <linux/spinlock.h>
+#include <linux/workqueue.h>
+#include <linux/platform_device.h>
+#include <linux/io.h>
+#include <linux/spi/spi.h>
+#include <linux/spi/spi_bitbang.h>
+#include <linux/bitops.h>
+#include <linux/gpio.h>
+
+#include <asm/mach-ar71xx/ar71xx.h>
+#include <asm/mach-ar71xx/platform.h>
+
+#define DRV_DESC	"Atheros PB44 SPI Controller driver"
+#define DRV_VERSION	"0.1.0"
+#define DRV_NAME	"pb44-spi"
+
+#undef PER_BIT_READ
+
+struct ar71xx_spi {
+	struct	spi_bitbang 	bitbang;
+	u32			ioc_base;
+	u32			reg_ctrl;
+
+	void __iomem 		*base;
+
+	struct platform_device	*pdev;
+};
+
+static inline u32 pb44_spi_rr(struct ar71xx_spi *sp, unsigned reg)
+{
+	return __raw_readl(sp->base + reg);
+}
+
+static inline void pb44_spi_wr(struct ar71xx_spi *sp, unsigned reg, u32 val)
+{
+	__raw_writel(val, sp->base + reg);
+}
+
+static inline struct ar71xx_spi *spidev_to_sp(struct spi_device *spi)
+{
+	return spi_master_get_devdata(spi->master);
+}
+
+static void pb44_spi_chipselect(struct spi_device *spi, int is_active)
+{
+	struct ar71xx_spi *sp = spidev_to_sp(spi);
+	int cs_high = (spi->mode & SPI_CS_HIGH) ? is_active : !is_active;
+
+	if (is_active) {
+		/* set initial clock polarity */
+		if (spi->mode & SPI_CPOL)
+			sp->ioc_base |= SPI_IOC_CLK;
+		else
+			sp->ioc_base &= ~SPI_IOC_CLK;
+
+		pb44_spi_wr(sp, SPI_REG_IOC, sp->ioc_base);
+	}
+
+	if (spi->chip_select) {
+		unsigned long gpio = (unsigned long) spi->controller_data;
+
+		/* SPI is normally active-low */
+		gpio_set_value(gpio, cs_high);
+	} else {
+		if (cs_high)
+			sp->ioc_base |= SPI_IOC_CS0;
+		else
+			sp->ioc_base &= ~SPI_IOC_CS0;
+
+		pb44_spi_wr(sp, SPI_REG_IOC, sp->ioc_base);
+	}
+
+}
+
+static int pb44_spi_setup_cs(struct spi_device *spi)
+{
+	struct ar71xx_spi *sp = spidev_to_sp(spi);
+
+	/* enable GPIO mode */
+	pb44_spi_wr(sp, SPI_REG_FS, SPI_FS_GPIO);
+
+	/* save CTRL register */
+	sp->reg_ctrl = pb44_spi_rr(sp, SPI_REG_CTRL);
+	sp->ioc_base = pb44_spi_rr(sp, SPI_REG_IOC);
+
+	/* TODO: setup speed? */
+	pb44_spi_wr(sp, SPI_REG_CTRL, 0x43);
+
+	if (spi->chip_select) {
+		unsigned long gpio = (unsigned long) spi->controller_data;
+		int status = 0;
+
+		status = gpio_request(gpio, dev_name(&spi->dev));
+		if (status)
+			return status;
+
+		status = gpio_direction_output(gpio, spi->mode & SPI_CS_HIGH);
+		if (status) {
+			gpio_free(gpio);
+			return status;
+		}
+	} else {
+		if (spi->mode & SPI_CS_HIGH)
+			sp->ioc_base |= SPI_IOC_CS0;
+		else
+			sp->ioc_base &= ~SPI_IOC_CS0;
+		pb44_spi_wr(sp, SPI_REG_IOC, sp->ioc_base);
+	}
+
+	return 0;
+}
+
+static void pb44_spi_cleanup_cs(struct spi_device *spi)
+{
+	struct ar71xx_spi *sp = spidev_to_sp(spi);
+
+	if (spi->chip_select) {
+		unsigned long gpio = (unsigned long) spi->controller_data;
+		gpio_free(gpio);
+	}
+
+	/* restore CTRL register */
+	pb44_spi_wr(sp, SPI_REG_CTRL, sp->reg_ctrl);
+	/* disable GPIO mode */
+	pb44_spi_wr(sp, SPI_REG_FS, 0);
+}
+
+static int pb44_spi_setup(struct spi_device *spi)
+{
+	int status = 0;
+
+	if (spi->bits_per_word > 32)
+		return -EINVAL;
+
+	if (!spi->controller_state) {
+		status = pb44_spi_setup_cs(spi);
+		if (status)
+			return status;
+	}
+
+	status = spi_bitbang_setup(spi);
+	if (status && !spi->controller_state)
+		pb44_spi_cleanup_cs(spi);
+
+	return status;
+}
+
+static void pb44_spi_cleanup(struct spi_device *spi)
+{
+	pb44_spi_cleanup_cs(spi);
+	spi_bitbang_cleanup(spi);
+}
+
+static u32 pb44_spi_txrx_mode0(struct spi_device *spi, unsigned nsecs,
+			       u32 word, u8 bits)
+{
+	struct ar71xx_spi *sp = spidev_to_sp(spi);
+	u32 ioc = sp->ioc_base;
+	u32 ret;
+
+	/* clock starts at inactive polarity */
+	for (word <<= (32 - bits); likely(bits); bits--) {
+		u32 out;
+
+		if (word & (1 << 31))
+			out = ioc | SPI_IOC_DO;
+		else
+			out = ioc & ~SPI_IOC_DO;
+
+		/* setup MSB (to slave) on trailing edge */
+		pb44_spi_wr(sp, SPI_REG_IOC, out);
+		pb44_spi_wr(sp, SPI_REG_IOC, out | SPI_IOC_CLK);
+
+		word <<= 1;
+
+#ifdef PER_BIT_READ
+		/* sample MSB (from slave) on leading edge */
+		ret = pb44_spi_rr(sp, SPI_REG_RDS);
+		pb44_spi_wr(sp, SPI_REG_IOC, out);
+#endif
+	}
+
+#ifndef PER_BIT_READ
+	ret = pb44_spi_rr(sp, SPI_REG_RDS);
+#endif
+	return ret;
+}
+
+static int pb44_spi_probe(struct platform_device *pdev)
+{
+	struct spi_master *master;
+	struct ar71xx_spi *sp;
+	struct ar71xx_spi_platform_data *pdata;
+	struct resource	*r;
+	int ret;
+
+	master = spi_alloc_master(&pdev->dev, sizeof(*sp));
+	if (master == NULL) {
+		dev_err(&pdev->dev, "failed to allocate spi master\n");
+		return -ENOMEM;
+	}
+
+	sp = spi_master_get_devdata(master);
+	platform_set_drvdata(pdev, sp);
+
+	pdata = pdev->dev.platform_data;
+
+	master->setup = pb44_spi_setup;
+	master->cleanup = pb44_spi_cleanup;
+	if (pdata) {
+		master->bus_num = pdata->bus_num;
+		master->num_chipselect = pdata->num_chipselect;
+	} else {
+		master->bus_num = 0;
+		master->num_chipselect = 1;
+	}
+
+	sp->bitbang.master = spi_master_get(master);
+	sp->bitbang.chipselect = pb44_spi_chipselect;
+	sp->bitbang.txrx_word[SPI_MODE_0] = pb44_spi_txrx_mode0;
+	sp->bitbang.setup_transfer = spi_bitbang_setup_transfer;
+	sp->bitbang.flags = SPI_CS_HIGH;
+
+	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (r == NULL) {
+		ret = -ENOENT;
+		goto err1;
+	}
+
+	sp->base = ioremap_nocache(r->start, r->end - r->start + 1);
+	if (!sp->base) {
+		ret = -ENXIO;
+		goto err1;
+	}
+
+	ret = spi_bitbang_start(&sp->bitbang);
+	if (!ret)
+		return 0;
+
+	iounmap(sp->base);
+ err1:
+	platform_set_drvdata(pdev, NULL);
+	spi_master_put(sp->bitbang.master);
+
+	return ret;
+}
+
+static int pb44_spi_remove(struct platform_device *pdev)
+{
+	struct ar71xx_spi *sp = platform_get_drvdata(pdev);
+
+	spi_bitbang_stop(&sp->bitbang);
+	iounmap(sp->base);
+	platform_set_drvdata(pdev, NULL);
+	spi_master_put(sp->bitbang.master);
+
+	return 0;
+}
+
+static struct platform_driver pb44_spi_drv = {
+	.probe		= pb44_spi_probe,
+	.remove		= pb44_spi_remove,
+	.driver		= {
+		.name	= DRV_NAME,
+		.owner	= THIS_MODULE,
+	},
+};
+
+static int __init pb44_spi_init(void)
+{
+	return platform_driver_register(&pb44_spi_drv);
+}
+module_init(pb44_spi_init);
+
+static void __exit pb44_spi_exit(void)
+{
+	platform_driver_unregister(&pb44_spi_drv);
+}
+module_exit(pb44_spi_exit);
+
+MODULE_ALIAS("platform:" DRV_NAME);
+MODULE_DESCRIPTION(DRV_DESC);
+MODULE_VERSION(DRV_VERSION);
+MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>");
+MODULE_LICENSE("GPL v2");