SPI: Add SPI controller driver for the Atheros AR71XX/AR724X/AR913X SoCs

The Atheros AR71XX/AR724X/AR913X SoCs have a built-in SPI controller. This
patch implements a driver for that.

Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
Cc: David Brownell <dbrownell@users.sourceforge.net>
Cc: spi-devel-general@lists.sourceforge.net
Acked-by: Grant Likely <grant.likely@secretlab.ca>
Cc: linux-mips@linux-mips.org
Cc: Imre Kaloz <kaloz@openwrt.org>
Cc: Luis R. Rodriguez <lrodriguez@atheros.com>
Cc: Cliff Holden <Cliff.Holden@Atheros.com>
Cc: Kathy Giori <Kathy.Giori@Atheros.com>
Patchwork: https://patchwork.linux-mips.org/patch/1960/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

3 files changed, 301 insertions, 0 deletions

diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index 13bfa9d48082..bb233a9cbad2 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -53,6 +53,14 @@ if SPI_MASTER
 
 comment "SPI Master Controller Drivers"
 
+config SPI_ATH79
+        tristate "Atheros AR71XX/AR724X/AR913X SPI controller driver"
+        depends on ATH79 && GENERIC_GPIO
+        select SPI_BITBANG
+        help
+          This enables support for the SPI controller present on the
+          Atheros AR71XX/AR724X/AR913X SoCs.
+
 config SPI_ATMEL
         tristate "Atmel SPI Controller"
         depends on (ARCH_AT91 || AVR32)
diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
index 3a42463c92a4..86d1b5f9bbd9 100644
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -10,6 +10,7 @@ obj-$(CONFIG_SPI_MASTER)		+= spi.o
 
 # SPI master controller drivers (bus)
 obj-$(CONFIG_SPI_ATMEL)                 += atmel_spi.o
+obj-$(CONFIG_SPI_ATH79)                 += ath79_spi.o
 obj-$(CONFIG_SPI_BFIN)                  += spi_bfin5xx.o
 obj-$(CONFIG_SPI_BITBANG)               += spi_bitbang.o
 obj-$(CONFIG_SPI_AU1550)                += au1550_spi.o
diff --git a/drivers/spi/ath79_spi.c b/drivers/spi/ath79_spi.c
new file mode 100644
index 000000000000..fcff810ea3b0
--- /dev/null
+++ b/drivers/spi/ath79_spi.c
@@ -0,0 +1,292 @@
+/*
+ * SPI controller driver for the Atheros AR71XX/AR724X/AR913X SoCs
+ *
+ * Copyright (C) 2009-2011 Gabor Juhos <juhosg@openwrt.org>
+ *
+ * This driver has been based on the spi-gpio.c:
+ *      Copyright (C) 2006,2008 David Brownell
+ *
+ * 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-ath79/ar71xx_regs.h>
+#include <asm/mach-ath79/ath79_spi_platform.h>
+
+#define DRV_NAME        "ath79-spi"
+
+struct ath79_spi {
+        struct spi_bitbang      bitbang;
+        u32                     ioc_base;
+        u32                     reg_ctrl;
+        void __iomem            *base;
+};
+
+static inline u32 ath79_spi_rr(struct ath79_spi *sp, unsigned reg)
+{
+        return ioread32(sp->base + reg);
+}
+
+static inline void ath79_spi_wr(struct ath79_spi *sp, unsigned reg, u32 val)
+{
+        iowrite32(val, sp->base + reg);
+}
+
+static inline struct ath79_spi *ath79_spidev_to_sp(struct spi_device *spi)
+{
+        return spi_master_get_devdata(spi->master);
+}
+
+static void ath79_spi_chipselect(struct spi_device *spi, int is_active)
+{
+        struct ath79_spi *sp = ath79_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 |= AR71XX_SPI_IOC_CLK;
+                else
+                        sp->ioc_base &= ~AR71XX_SPI_IOC_CLK;
+
+                ath79_spi_wr(sp, AR71XX_SPI_REG_IOC, sp->ioc_base);
+        }
+
+        if (spi->chip_select) {
+                struct ath79_spi_controller_data *cdata = spi->controller_data;
+
+                /* SPI is normally active-low */
+                gpio_set_value(cdata->gpio, cs_high);
+        } else {
+                if (cs_high)
+                        sp->ioc_base |= AR71XX_SPI_IOC_CS0;
+                else
+                        sp->ioc_base &= ~AR71XX_SPI_IOC_CS0;
+
+                ath79_spi_wr(sp, AR71XX_SPI_REG_IOC, sp->ioc_base);
+        }
+
+}
+
+static int ath79_spi_setup_cs(struct spi_device *spi)
+{
+        struct ath79_spi *sp = ath79_spidev_to_sp(spi);
+        struct ath79_spi_controller_data *cdata;
+
+        cdata = spi->controller_data;
+        if (spi->chip_select && !cdata)
+                return -EINVAL;
+
+        /* enable GPIO mode */
+        ath79_spi_wr(sp, AR71XX_SPI_REG_FS, AR71XX_SPI_FS_GPIO);
+
+        /* save CTRL register */
+        sp->reg_ctrl = ath79_spi_rr(sp, AR71XX_SPI_REG_CTRL);
+        sp->ioc_base = ath79_spi_rr(sp, AR71XX_SPI_REG_IOC);
+
+        /* TODO: setup speed? */
+        ath79_spi_wr(sp, AR71XX_SPI_REG_CTRL, 0x43);
+
+        if (spi->chip_select) {
+                int status = 0;
+
+                status = gpio_request(cdata->gpio, dev_name(&spi->dev));
+                if (status)
+                        return status;
+
+                status = gpio_direction_output(cdata->gpio,
+                                               spi->mode & SPI_CS_HIGH);
+                if (status) {
+                        gpio_free(cdata->gpio);
+                        return status;
+                }
+        } else {
+                if (spi->mode & SPI_CS_HIGH)
+                        sp->ioc_base |= AR71XX_SPI_IOC_CS0;
+                else
+                        sp->ioc_base &= ~AR71XX_SPI_IOC_CS0;
+                ath79_spi_wr(sp, AR71XX_SPI_REG_IOC, sp->ioc_base);
+        }
+
+        return 0;
+}
+
+static void ath79_spi_cleanup_cs(struct spi_device *spi)
+{
+        struct ath79_spi *sp = ath79_spidev_to_sp(spi);
+
+        if (spi->chip_select) {
+                struct ath79_spi_controller_data *cdata = spi->controller_data;
+                gpio_free(cdata->gpio);
+        }
+
+        /* restore CTRL register */
+        ath79_spi_wr(sp, AR71XX_SPI_REG_CTRL, sp->reg_ctrl);
+        /* disable GPIO mode */
+        ath79_spi_wr(sp, AR71XX_SPI_REG_FS, 0);
+}
+
+static int ath79_spi_setup(struct spi_device *spi)
+{
+        int status = 0;
+
+        if (spi->bits_per_word > 32)
+                return -EINVAL;
+
+        if (!spi->controller_state) {
+                status = ath79_spi_setup_cs(spi);
+                if (status)
+                        return status;
+        }
+
+        status = spi_bitbang_setup(spi);
+        if (status && !spi->controller_state)
+                ath79_spi_cleanup_cs(spi);
+
+        return status;
+}
+
+static void ath79_spi_cleanup(struct spi_device *spi)
+{
+        ath79_spi_cleanup_cs(spi);
+        spi_bitbang_cleanup(spi);
+}
+
+static u32 ath79_spi_txrx_mode0(struct spi_device *spi, unsigned nsecs,
+                               u32 word, u8 bits)
+{
+        struct ath79_spi *sp = ath79_spidev_to_sp(spi);
+        u32 ioc = sp->ioc_base;
+
+        /* clock starts at inactive polarity */
+        for (word <<= (32 - bits); likely(bits); bits--) {
+                u32 out;
+
+                if (word & (1 << 31))
+                        out = ioc | AR71XX_SPI_IOC_DO;
+                else
+                        out = ioc & ~AR71XX_SPI_IOC_DO;
+
+                /* setup MSB (to slave) on trailing edge */
+                ath79_spi_wr(sp, AR71XX_SPI_REG_IOC, out);
+                ath79_spi_wr(sp, AR71XX_SPI_REG_IOC, out | AR71XX_SPI_IOC_CLK);
+
+                word <<= 1;
+        }
+
+        return ath79_spi_rr(sp, AR71XX_SPI_REG_RDS);
+}
+
+static __devinit int ath79_spi_probe(struct platform_device *pdev)
+{
+        struct spi_master *master;
+        struct ath79_spi *sp;
+        struct ath79_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 = ath79_spi_setup;
+        master->cleanup = ath79_spi_cleanup;
+        if (pdata) {
+                master->bus_num = pdata->bus_num;
+                master->num_chipselect = pdata->num_chipselect;
+        } else {
+                master->bus_num = -1;
+                master->num_chipselect = 1;
+        }
+
+        sp->bitbang.master = spi_master_get(master);
+        sp->bitbang.chipselect = ath79_spi_chipselect;
+        sp->bitbang.txrx_word[SPI_MODE_0] = ath79_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 err_put_master;
+        }
+
+        sp->base = ioremap(r->start, r->end - r->start + 1);
+        if (!sp->base) {
+                ret = -ENXIO;
+                goto err_put_master;
+        }
+
+        ret = spi_bitbang_start(&sp->bitbang);
+        if (ret)
+                goto err_unmap;
+
+        return 0;
+
+err_unmap:
+        iounmap(sp->base);
+err_put_master:
+        platform_set_drvdata(pdev, NULL);
+        spi_master_put(sp->bitbang.master);
+
+        return ret;
+}
+
+static __devexit int ath79_spi_remove(struct platform_device *pdev)
+{
+        struct ath79_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 ath79_spi_driver = {
+        .probe          = ath79_spi_probe,
+        .remove         = __devexit_p(ath79_spi_remove),
+        .driver         = {
+                .name   = DRV_NAME,
+                .owner  = THIS_MODULE,
+        },
+};
+
+static __init int ath79_spi_init(void)
+{
+        return platform_driver_register(&ath79_spi_driver);
+}
+module_init(ath79_spi_init);
+
+static __exit void ath79_spi_exit(void)
+{
+        platform_driver_unregister(&ath79_spi_driver);
+}
+module_exit(ath79_spi_exit);
+
+MODULE_DESCRIPTION("SPI controller driver for Atheros AR71XX/AR724X/AR913X");
+MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:" DRV_NAME);