[PATCH] spi: add spi master driver for Freescale MPC83xx SPI controller

This driver supports the SPI controller on the MPC83xx SoC devices from
Freescale.  Note, this driver supports only the simple shift register SPI
controller and not the descriptor based CPM or QUICCEngine SPI controller.

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

3 files changed, 496 insertions, 0 deletions

diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index 9ce1d01..3867c6e 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -75,6 +75,18 @@ config SPI_BUTTERFLY
 	  inexpensive battery powered microcontroller evaluation board.
 	  This same cable can be used to flash new firmware.
 
+config SPI_MPC83xx
+	tristate "Freescale MPC83xx SPI controller"
+	depends on SPI_MASTER && PPC_83xx && EXPERIMENTAL
+	select SPI_BITBANG
+	help
+	  This enables using the Freescale MPC83xx SPI controller in master
+	  mode.
+
+	  Note, this driver uniquely supports the SPI controller on the MPC83xx
+	  family of PowerPC processors.  The MPC83xx uses a simple set of shift
+	  registers for data (opposed to the CPM based descriptor model).
+
 config SPI_PXA2XX
 	tristate "PXA2xx SSP SPI master"
 	depends on SPI_MASTER && ARCH_PXA && EXPERIMENTAL
diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
index 1bca5f9..5a410ca 100644
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -14,6 +14,7 @@ obj-$(CONFIG_SPI_MASTER)		+= spi.o
 obj-$(CONFIG_SPI_BITBANG)		+= spi_bitbang.o
 obj-$(CONFIG_SPI_BUTTERFLY)		+= spi_butterfly.o
 obj-$(CONFIG_SPI_PXA2XX)		+= pxa2xx_spi.o
+obj-$(CONFIG_SPI_MPC83xx)		+= spi_mpc83xx.o
 # 	... add above this line ...
 
 # SPI protocol drivers (device/link on bus)
diff --git a/drivers/spi/spi_mpc83xx.c b/drivers/spi/spi_mpc83xx.c
new file mode 100644
index 0000000..5d92a7e
--- /dev/null
+++ b/drivers/spi/spi_mpc83xx.c
@@ -0,0 +1,483 @@
+/*
+ * MPC83xx SPI controller driver.
+ *
+ * Maintainer: Kumar Gala
+ *
+ * Copyright (C) 2006 Polycom, Inc.
+ *
+ * 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.
+ */
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/completion.h>
+#include <linux/interrupt.h>
+#include <linux/delay.h>
+#include <linux/irq.h>
+#include <linux/device.h>
+#include <linux/spi/spi.h>
+#include <linux/spi/spi_bitbang.h>
+#include <linux/platform_device.h>
+#include <linux/fsl_devices.h>
+
+#include <asm/irq.h>
+#include <asm/io.h>
+
+/* SPI Controller registers */
+struct mpc83xx_spi_reg {
+	u8 res1[0x20];
+	__be32 mode;
+	__be32 event;
+	__be32 mask;
+	__be32 command;
+	__be32 transmit;
+	__be32 receive;
+};
+
+/* SPI Controller mode register definitions */
+#define	SPMODE_CI_INACTIVEHIGH	(1 << 29)
+#define	SPMODE_CP_BEGIN_EDGECLK	(1 << 28)
+#define	SPMODE_DIV16		(1 << 27)
+#define	SPMODE_REV		(1 << 26)
+#define	SPMODE_MS		(1 << 25)
+#define	SPMODE_ENABLE		(1 << 24)
+#define	SPMODE_LEN(x)		((x) << 20)
+#define	SPMODE_PM(x)		((x) << 16)
+
+/*
+ * Default for SPI Mode:
+ * 	SPI MODE 0 (inactive low, phase middle, MSB, 8-bit length, slow clk
+ */
+#define	SPMODE_INIT_VAL (SPMODE_CI_INACTIVEHIGH | SPMODE_DIV16 | SPMODE_REV | \
+			 SPMODE_MS | SPMODE_LEN(7) | SPMODE_PM(0xf))
+
+/* SPIE register values */
+#define	SPIE_NE		0x00000200	/* Not empty */
+#define	SPIE_NF		0x00000100	/* Not full */
+
+/* SPIM register values */
+#define	SPIM_NE		0x00000200	/* Not empty */
+#define	SPIM_NF		0x00000100	/* Not full */
+
+/* SPI Controller driver's private data. */
+struct mpc83xx_spi {
+	/* bitbang has to be first */
+	struct spi_bitbang bitbang;
+	struct completion done;
+
+	struct mpc83xx_spi_reg __iomem *base;
+
+	/* rx & tx bufs from the spi_transfer */
+	const void *tx;
+	void *rx;
+
+	/* functions to deal with different sized buffers */
+	void (*get_rx) (u32 rx_data, struct mpc83xx_spi *);
+	u32(*get_tx) (struct mpc83xx_spi *);
+
+	unsigned int count;
+	u32 irq;
+
+	unsigned nsecs;		/* (clock cycle time)/2 */
+
+	u32 sysclk;
+	void (*activate_cs) (u8 cs, u8 polarity);
+	void (*deactivate_cs) (u8 cs, u8 polarity);
+};
+
+static inline void mpc83xx_spi_write_reg(__be32 __iomem * reg, u32 val)
+{
+	out_be32(reg, val);
+}
+
+static inline u32 mpc83xx_spi_read_reg(__be32 __iomem * reg)
+{
+	return in_be32(reg);
+}
+
+#define MPC83XX_SPI_RX_BUF(type) 					  \
+void mpc83xx_spi_rx_buf_##type(u32 data, struct mpc83xx_spi *mpc83xx_spi) \
+{									  \
+	type * rx = mpc83xx_spi->rx;					  \
+	*rx++ = (type)data;						  \
+	mpc83xx_spi->rx = rx;						  \
+}
+
+#define MPC83XX_SPI_TX_BUF(type)				\
+u32 mpc83xx_spi_tx_buf_##type(struct mpc83xx_spi *mpc83xx_spi)	\
+{								\
+	u32 data;						\
+	const type * tx = mpc83xx_spi->tx;			\
+	data = *tx++;						\
+	mpc83xx_spi->tx = tx;					\
+	return data;						\
+}
+
+MPC83XX_SPI_RX_BUF(u8)
+MPC83XX_SPI_RX_BUF(u16)
+MPC83XX_SPI_RX_BUF(u32)
+MPC83XX_SPI_TX_BUF(u8)
+MPC83XX_SPI_TX_BUF(u16)
+MPC83XX_SPI_TX_BUF(u32)
+
+static void mpc83xx_spi_chipselect(struct spi_device *spi, int value)
+{
+	struct mpc83xx_spi *mpc83xx_spi;
+	u8 pol = spi->mode & SPI_CS_HIGH ? 1 : 0;
+
+	mpc83xx_spi = spi_master_get_devdata(spi->master);
+
+	if (value == BITBANG_CS_INACTIVE) {
+		if (mpc83xx_spi->deactivate_cs)
+			mpc83xx_spi->deactivate_cs(spi->chip_select, pol);
+	}
+
+	if (value == BITBANG_CS_ACTIVE) {
+		u32 regval = mpc83xx_spi_read_reg(&mpc83xx_spi->base->mode);
+		u32 len = spi->bits_per_word;
+		if (len == 32)
+			len = 0;
+		else
+			len = len - 1;
+
+		/* mask out bits we are going to set */
+		regval &= ~0x38ff0000;
+
+		if (spi->mode & SPI_CPHA)
+			regval |= SPMODE_CP_BEGIN_EDGECLK;
+		if (spi->mode & SPI_CPOL)
+			regval |= SPMODE_CI_INACTIVEHIGH;
+
+		regval |= SPMODE_LEN(len);
+
+		if ((mpc83xx_spi->sysclk / spi->max_speed_hz) >= 64) {
+			u8 pm = mpc83xx_spi->sysclk / (spi->max_speed_hz * 64);
+			regval |= SPMODE_PM(pm) | SPMODE_DIV16;
+		} else {
+			u8 pm = mpc83xx_spi->sysclk / (spi->max_speed_hz * 4);
+			regval |= SPMODE_PM(pm);
+		}
+
+		mpc83xx_spi_write_reg(&mpc83xx_spi->base->mode, regval);
+		if (mpc83xx_spi->activate_cs)
+			mpc83xx_spi->activate_cs(spi->chip_select, pol);
+	}
+}
+
+static
+int mpc83xx_spi_setup_transfer(struct spi_device *spi, struct spi_transfer *t)
+{
+	struct mpc83xx_spi *mpc83xx_spi;
+	u32 regval;
+	u8 bits_per_word;
+	u32 hz;
+
+	mpc83xx_spi = spi_master_get_devdata(spi->master);
+
+	if (t) {
+		bits_per_word = t->bits_per_word;
+		hz = t->speed_hz;
+	} else {
+		bits_per_word = 0;
+		hz = 0;
+	}
+
+	/* spi_transfer level calls that work per-word */
+	if (!bits_per_word)
+		bits_per_word = spi->bits_per_word;
+
+	/* Make sure its a bit width we support [4..16, 32] */
+	if ((bits_per_word < 4)
+	    || ((bits_per_word > 16) && (bits_per_word != 32)))
+		return -EINVAL;
+
+	if (bits_per_word <= 8) {
+		mpc83xx_spi->get_rx = mpc83xx_spi_rx_buf_u8;
+		mpc83xx_spi->get_tx = mpc83xx_spi_tx_buf_u8;
+	} else if (bits_per_word <= 16) {
+		mpc83xx_spi->get_rx = mpc83xx_spi_rx_buf_u16;
+		mpc83xx_spi->get_tx = mpc83xx_spi_tx_buf_u16;
+	} else if (bits_per_word <= 32) {
+		mpc83xx_spi->get_rx = mpc83xx_spi_rx_buf_u32;
+		mpc83xx_spi->get_tx = mpc83xx_spi_tx_buf_u32;
+	} else
+		return -EINVAL;
+
+	/* nsecs = (clock period)/2 */
+	if (!hz)
+		hz = spi->max_speed_hz;
+	mpc83xx_spi->nsecs = (1000000000 / 2) / hz;
+	if (mpc83xx_spi->nsecs > MAX_UDELAY_MS * 1000)
+		return -EINVAL;
+
+	if (bits_per_word == 32)
+		bits_per_word = 0;
+	else
+		bits_per_word = bits_per_word - 1;
+
+	regval = mpc83xx_spi_read_reg(&mpc83xx_spi->base->mode);
+
+	/* Mask out bits_per_wordgth */
+	regval &= 0xff0fffff;
+	regval |= SPMODE_LEN(bits_per_word);
+
+	mpc83xx_spi_write_reg(&mpc83xx_spi->base->mode, regval);
+
+	return 0;
+}
+
+static int mpc83xx_spi_setup(struct spi_device *spi)
+{
+	struct spi_bitbang *bitbang;
+	struct mpc83xx_spi *mpc83xx_spi;
+	int retval;
+
+	if (!spi->max_speed_hz)
+		return -EINVAL;
+
+	bitbang = spi_master_get_devdata(spi->master);
+	mpc83xx_spi = spi_master_get_devdata(spi->master);
+
+	if (!spi->bits_per_word)
+		spi->bits_per_word = 8;
+
+	retval = mpc83xx_spi_setup_transfer(spi, NULL);
+	if (retval < 0)
+		return retval;
+
+	dev_dbg(&spi->dev, "%s, mode %d, %u bits/w, %u nsec\n",
+		__FUNCTION__, spi->mode & (SPI_CPOL | SPI_CPHA),
+		spi->bits_per_word, 2 * mpc83xx_spi->nsecs);
+
+	/* NOTE we _need_ to call chipselect() early, ideally with adapter
+	 * setup, unless the hardware defaults cooperate to avoid confusion
+	 * between normal (active low) and inverted chipselects.
+	 */
+
+	/* deselect chip (low or high) */
+	spin_lock(&bitbang->lock);
+	if (!bitbang->busy) {
+		bitbang->chipselect(spi, BITBANG_CS_INACTIVE);
+		ndelay(mpc83xx_spi->nsecs);
+	}
+	spin_unlock(&bitbang->lock);
+
+	return 0;
+}
+
+static int mpc83xx_spi_bufs(struct spi_device *spi, struct spi_transfer *t)
+{
+	struct mpc83xx_spi *mpc83xx_spi;
+	u32 word;
+
+	mpc83xx_spi = spi_master_get_devdata(spi->master);
+
+	mpc83xx_spi->tx = t->tx_buf;
+	mpc83xx_spi->rx = t->rx_buf;
+	mpc83xx_spi->count = t->len;
+	INIT_COMPLETION(mpc83xx_spi->done);
+
+	/* enable rx ints */
+	mpc83xx_spi_write_reg(&mpc83xx_spi->base->mask, SPIM_NE);
+
+	/* transmit word */
+	word = mpc83xx_spi->get_tx(mpc83xx_spi);
+	mpc83xx_spi_write_reg(&mpc83xx_spi->base->transmit, word);
+
+	wait_for_completion(&mpc83xx_spi->done);
+
+	/* disable rx ints */
+	mpc83xx_spi_write_reg(&mpc83xx_spi->base->mask, 0);
+
+	return t->len - mpc83xx_spi->count;
+}
+
+irqreturn_t mpc83xx_spi_irq(s32 irq, void *context_data,
+			    struct pt_regs * ptregs)
+{
+	struct mpc83xx_spi *mpc83xx_spi = context_data;
+	u32 event;
+	irqreturn_t ret = IRQ_NONE;
+
+	/* Get interrupt events(tx/rx) */
+	event = mpc83xx_spi_read_reg(&mpc83xx_spi->base->event);
+
+	/* We need handle RX first */
+	if (event & SPIE_NE) {
+		u32 rx_data = mpc83xx_spi_read_reg(&mpc83xx_spi->base->receive);
+
+		if (mpc83xx_spi->rx)
+			mpc83xx_spi->get_rx(rx_data, mpc83xx_spi);
+
+		ret = IRQ_HANDLED;
+	}
+
+	if ((event & SPIE_NF) == 0)
+		/* spin until TX is done */
+		while (((event =
+			 mpc83xx_spi_read_reg(&mpc83xx_spi->base->event)) &
+						SPIE_NF) == 0)
+			 cpu_relax();
+
+	mpc83xx_spi->count -= 1;
+	if (mpc83xx_spi->count) {
+		if (mpc83xx_spi->tx) {
+			u32 word = mpc83xx_spi->get_tx(mpc83xx_spi);
+			mpc83xx_spi_write_reg(&mpc83xx_spi->base->transmit,
+					      word);
+		}
+	} else {
+		complete(&mpc83xx_spi->done);
+	}
+
+	/* Clear the events */
+	mpc83xx_spi_write_reg(&mpc83xx_spi->base->event, event);
+
+	return ret;
+}
+
+static int __init mpc83xx_spi_probe(struct platform_device *dev)
+{
+	struct spi_master *master;
+	struct mpc83xx_spi *mpc83xx_spi;
+	struct fsl_spi_platform_data *pdata;
+	struct resource *r;
+	u32 regval;
+	int ret = 0;
+
+	/* Get resources(memory, IRQ) associated with the device */
+	master = spi_alloc_master(&dev->dev, sizeof(struct mpc83xx_spi));
+
+	if (master == NULL) {
+		ret = -ENOMEM;
+		goto err;
+	}
+
+	platform_set_drvdata(dev, master);
+	pdata = dev->dev.platform_data;
+
+	if (pdata == NULL) {
+		ret = -ENODEV;
+		goto free_master;
+	}
+
+	r = platform_get_resource(dev, IORESOURCE_MEM, 0);
+	if (r == NULL) {
+		ret = -ENODEV;
+		goto free_master;
+	}
+
+	mpc83xx_spi = spi_master_get_devdata(master);
+	mpc83xx_spi->bitbang.master = spi_master_get(master);
+	mpc83xx_spi->bitbang.chipselect = mpc83xx_spi_chipselect;
+	mpc83xx_spi->bitbang.setup_transfer = mpc83xx_spi_setup_transfer;
+	mpc83xx_spi->bitbang.txrx_bufs = mpc83xx_spi_bufs;
+	mpc83xx_spi->sysclk = pdata->sysclk;
+	mpc83xx_spi->activate_cs = pdata->activate_cs;
+	mpc83xx_spi->deactivate_cs = pdata->deactivate_cs;
+	mpc83xx_spi->get_rx = mpc83xx_spi_rx_buf_u8;
+	mpc83xx_spi->get_tx = mpc83xx_spi_tx_buf_u8;
+
+	mpc83xx_spi->bitbang.master->setup = mpc83xx_spi_setup;
+	init_completion(&mpc83xx_spi->done);
+
+	mpc83xx_spi->base = ioremap(r->start, r->end - r->start + 1);
+	if (mpc83xx_spi->base == NULL) {
+		ret = -ENOMEM;
+		goto put_master;
+	}
+
+	mpc83xx_spi->irq = platform_get_irq(dev, 0);
+
+	if (mpc83xx_spi->irq < 0) {
+		ret = -ENXIO;
+		goto unmap_io;
+	}
+
+	/* Register for SPI Interrupt */
+	ret = request_irq(mpc83xx_spi->irq, mpc83xx_spi_irq,
+			  0, "mpc83xx_spi", mpc83xx_spi);
+
+	if (ret != 0)
+		goto unmap_io;
+
+	master->bus_num = pdata->bus_num;
+	master->num_chipselect = pdata->max_chipselect;
+
+	/* SPI controller initializations */
+	mpc83xx_spi_write_reg(&mpc83xx_spi->base->mode, 0);
+	mpc83xx_spi_write_reg(&mpc83xx_spi->base->mask, 0);
+	mpc83xx_spi_write_reg(&mpc83xx_spi->base->command, 0);
+	mpc83xx_spi_write_reg(&mpc83xx_spi->base->event, 0xffffffff);
+
+	/* Enable SPI interface */
+	regval = pdata->initial_spmode | SPMODE_INIT_VAL | SPMODE_ENABLE;
+	mpc83xx_spi_write_reg(&mpc83xx_spi->base->mode, regval);
+
+	ret = spi_bitbang_start(&mpc83xx_spi->bitbang);
+
+	if (ret != 0)
+		goto free_irq;
+
+	printk(KERN_INFO
+	       "%s: MPC83xx SPI Controller driver at 0x%p (irq = %d)\n",
+	       dev->dev.bus_id, mpc83xx_spi->base, mpc83xx_spi->irq);
+
+	return ret;
+
+free_irq:
+	free_irq(mpc83xx_spi->irq, mpc83xx_spi);
+unmap_io:
+	iounmap(mpc83xx_spi->base);
+put_master:
+	spi_master_put(master);
+free_master:
+	kfree(master);
+err:
+	return ret;
+}
+
+static int __devexit mpc83xx_spi_remove(struct platform_device *dev)
+{
+	struct mpc83xx_spi *mpc83xx_spi;
+	struct spi_master *master;
+
+	master = platform_get_drvdata(dev);
+	mpc83xx_spi = spi_master_get_devdata(master);
+
+	spi_bitbang_stop(&mpc83xx_spi->bitbang);
+	free_irq(mpc83xx_spi->irq, mpc83xx_spi);
+	iounmap(mpc83xx_spi->base);
+	spi_master_put(mpc83xx_spi->bitbang.master);
+
+	return 0;
+}
+
+static struct platform_driver mpc83xx_spi_driver = {
+	.probe = mpc83xx_spi_probe,
+	.remove = __devexit_p(mpc83xx_spi_remove),
+	.driver = {
+		   .name = "mpc83xx_spi",
+	},
+};
+
+static int __init mpc83xx_spi_init(void)
+{
+	return platform_driver_register(&mpc83xx_spi_driver);
+}
+
+static void __exit mpc83xx_spi_exit(void)
+{
+	platform_driver_unregister(&mpc83xx_spi_driver);
+}
+
+module_init(mpc83xx_spi_init);
+module_exit(mpc83xx_spi_exit);
+
+MODULE_AUTHOR("Kumar Gala");
+MODULE_DESCRIPTION("Simple MPC83xx SPI Driver");
+MODULE_LICENSE("GPL");