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[RFC 11/18] spi: add SPI controller driver for the Atheros AR71XX/AR724X

To: Ralf Baechle <ralf@linux-mips.org>
Subject: [RFC 11/18] spi: add SPI controller driver for the Atheros AR71XX/AR724X/AR913X SoCs
From: Gabor Juhos <juhosg@openwrt.org>
Date: Fri, 12 Nov 2010 22:51:17 +0100
Cc: linux-mips@linux-mips.org, "Luis R. Rodriguez" <mcgrof@gmail.com>, Cliff Holden <Cliff.Holden@Atheros.com>, Imre Kaloz <kaloz@openwrt.org>, Gabor Juhos <juhosg@openwrt.org>, David Brownell <dbrownell@users.sourceforge.net>, spi-devel-general@lists.sourceforge.net
In-reply-to: <1289598684-30624-1-git-send-email-juhosg@openwrt.org>
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <1289598684-30624-1-git-send-email-juhosg@openwrt.org>
Sender: linux-mips-bounce@linux-mips.org
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
---
Sorry for sending this twice, i forgot to add some CCs in the first round.

 .../include/asm/mach-ath79/ath79_spi_platform.h    |   19 ++
 drivers/spi/Kconfig                                |    8 +
 drivers/spi/Makefile                               |    1 +
 drivers/spi/ath79_spi.c                            |  291 ++++++++++++++++++++
 4 files changed, 319 insertions(+), 0 deletions(-)
 create mode 100644 arch/mips/include/asm/mach-ath79/ath79_spi_platform.h
 create mode 100644 drivers/spi/ath79_spi.c

diff --git a/arch/mips/include/asm/mach-ath79/ath79_spi_platform.h 
b/arch/mips/include/asm/mach-ath79/ath79_spi_platform.h
new file mode 100644
index 0000000..aa71216
--- /dev/null
+++ b/arch/mips/include/asm/mach-ath79/ath79_spi_platform.h
@@ -0,0 +1,19 @@
+/*
+ *  Platform data definition for Atheros AR71XX/AR724X/AR913X SPI controller
+ *
+ *  Copyright (C) 2008-2010 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.
+ */
+
+#ifndef _ATH79_SPI_PLATFORM_H
+#define _ATH79_SPI_PLATFORM_H
+
+struct ath79_spi_platform_data {
+       unsigned        bus_num;
+       unsigned        num_chipselect;
+};
+
+#endif /* _ATH79_SPI_PLATFORM_H */
diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index 78f9fd0..f2093e1 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 8bc1a5a..875bc3d 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 0000000..9b9f9cf
--- /dev/null
+++ b/drivers/spi/ath79_spi.c
@@ -0,0 +1,291 @@
+/*
+ * SPI controller driver for the Atheros AR71XX/AR724X/AR913X SoCs
+ *
+ * Copyright (C) 2009-2010 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_DESC       "SPI controller driver for Atheros AR71XX/AR724X/AR91X"
+#define DRV_NAME       "ath79-spi"
+
+struct ath79_spi {
+       struct  spi_bitbang     bitbang;
+       u32                     ioc_base;
+       u32                     reg_ctrl;
+
+       void __iomem            *base;
+
+       struct platform_device  *pdev;
+};
+
+static inline u32 ath79_spi_rr(struct ath79_spi *sp, unsigned reg)
+{
+       return __raw_readl(sp->base + reg);
+}
+
+static inline void ath79_spi_wr(struct ath79_spi *sp, unsigned reg, u32 val)
+{
+       __raw_writel(val, sp->base + reg);
+}
+
+static inline struct ath79_spi *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 = 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) {
+               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 |= 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 = spidev_to_sp(spi);
+
+       /* 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) {
+               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 |= 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 = spidev_to_sp(spi);
+
+       if (spi->chip_select) {
+               unsigned long gpio = (unsigned long) spi->controller_data;
+               gpio_free(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 = 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 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 = 0;
+               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 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_drv = {
+       .probe          = ath79_spi_probe,
+       .remove         = ath79_spi_remove,
+       .driver         = {
+               .name   = DRV_NAME,
+               .owner  = THIS_MODULE,
+       },
+};
+
+static int __init ath79_spi_init(void)
+{
+       return platform_driver_register(&ath79_spi_drv);
+}
+module_init(ath79_spi_init);
+
+static void __exit ath79_spi_exit(void)
+{
+       platform_driver_unregister(&ath79_spi_drv);
+}
+module_exit(ath79_spi_exit);
+
+MODULE_DESCRIPTION(DRV_DESC);
+MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:" DRV_NAME);
-- 
1.7.2.1


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