Subject: [PATCH v4] powerpc/5200: Add mpc5200-spi (non-PSC) device driver

From: Grant Likely <[email-masked]>
Date: Wed, 17 Jun 2009 20:55:01 -0600

From: Grant Likely <[email-masked]>

Adds support for the dedicated SPI device on the Freescale MPC5200(b)
SoC.

Signed-off-by: Grant Likely <[email-masked]>
---

Hi David,

It's been a while since I've posted this, but I believe I've addressed
all the outstanding comments against v3, and people are asking me for it.
The pre-message stuff is all gone and the error handling should be
better now.

BTW, the premessage stuff was to handle a platform I had where some of
the CS lines were controlled with a separate SPI transaction to the
same SPI controller.  It almost looks like an SPI bridge.  It requires
more thought before I try again.

Being a new driver, it would be nice to get it into 2.6.31, but
definitely not critical.

g.

 drivers/spi/Kconfig             |    8 +
 drivers/spi/Makefile            |    1 
 drivers/spi/mpc52xx_spi.c       |  520 +++++++++++++++++++++++++++++++++++++++
 include/linux/spi/mpc52xx_spi.h |   10 +
 4 files changed, 539 insertions(+), 0 deletions(-)
 create mode 100644 drivers/spi/mpc52xx_spi.c
 create mode 100644 include/linux/spi/mpc52xx_spi.h

diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index 83a185d..1994bcd 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -132,6 +132,14 @@ config SPI_LM70_LLP
 	  which interfaces to an LM70 temperature sensor using
 	  a parallel port.
 
+config SPI_MPC52xx
+	tristate "Freescale MPC52xx SPI (non-PSC) controller support"
+	depends on PPC_MPC52xx && SPI
+	select SPI_MASTER_OF
+	help
+	  This drivers supports the MPC52xx SPI controller in master SPI
+	  mode.
+
 config SPI_MPC52xx_PSC
 	tristate "Freescale MPC52xx PSC SPI controller"
 	depends on PPC_MPC52xx && EXPERIMENTAL
diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
index 5d04519..8de32c7 100644
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -24,6 +24,7 @@ obj-$(CONFIG_SPI_OMAP_UWIRE)		+= omap_uwire.o
 obj-$(CONFIG_SPI_OMAP24XX)		+= omap2_mcspi.o
 obj-$(CONFIG_SPI_ORION)			+= orion_spi.o
 obj-$(CONFIG_SPI_MPC52xx_PSC)		+= mpc52xx_psc_spi.o
+obj-$(CONFIG_SPI_MPC52xx)		+= mpc52xx_spi.o
 obj-$(CONFIG_SPI_MPC83xx)		+= spi_mpc83xx.o
 obj-$(CONFIG_SPI_S3C24XX_GPIO)		+= spi_s3c24xx_gpio.o
 obj-$(CONFIG_SPI_S3C24XX)		+= spi_s3c24xx.o
diff --git a/drivers/spi/mpc52xx_spi.c b/drivers/spi/mpc52xx_spi.c
new file mode 100644
index 0000000..ef8379b
--- /dev/null
+++ b/drivers/spi/mpc52xx_spi.c
@@ -0,0 +1,520 @@
+/*
+ * MPC52xx SPI bus driver.
+ *
+ * Copyright (C) 2008 Secret Lab Technologies Ltd.
+ *
+ * This file is released under the GPLv2
+ *
+ * This is the driver for the MPC5200's dedicated SPI controller.
+ *
+ * Note: this driver does not support the MPC5200 PSC in SPI mode.  For
+ * that driver see drivers/spi/mpc52xx_psc_spi.c
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/errno.h>
+#include <linux/of_platform.h>
+#include <linux/interrupt.h>
+#include <linux/delay.h>
+#include <linux/spi/spi.h>
+#include <linux/spi/mpc52xx_spi.h>
+#include <linux/of_spi.h>
+#include <linux/io.h>
+#include <asm/time.h>
+#include <asm/mpc52xx.h>
+
+MODULE_AUTHOR("Grant Likely <[email-masked]>");
+MODULE_DESCRIPTION("MPC52xx SPI (non-PSC) Driver");
+MODULE_LICENSE("GPL");
+
+/* Register offsets */
+#define SPI_CTRL1	0x00
+#define SPI_CTRL1_SPIE		(1 << 7)
+#define SPI_CTRL1_SPE		(1 << 6)
+#define SPI_CTRL1_MSTR		(1 << 4)
+#define SPI_CTRL1_CPOL		(1 << 3)
+#define SPI_CTRL1_CPHA		(1 << 2)
+#define SPI_CTRL1_SSOE		(1 << 1)
+#define SPI_CTRL1_LSBFE		(1 << 0)
+
+#define SPI_CTRL2	0x01
+#define SPI_BRR		0x04
+
+#define SPI_STATUS	0x05
+#define SPI_STATUS_SPIF		(1 << 7)
+#define SPI_STATUS_WCOL		(1 << 6)
+#define SPI_STATUS_MODF		(1 << 4)
+
+#define SPI_DATA	0x09
+#define SPI_PORTDATA	0x0d
+#define SPI_DATADIR	0x10
+
+/* FSM state return values */
+#define FSM_STOP	0	/* Nothing more for the state machine to */
+				/* do.  If something interesting happens */
+				/* then and IRQ will be received */
+#define FSM_POLL	1	/* need to poll for completion, an IRQ is */
+				/* not expected */
+#define FSM_CONTINUE	2	/* Keep iterating the state machine */
+
+/* Driver internal data */
+struct mpc52xx_spi {
+	struct spi_master *master;
+	u32 sysclk;
+	void __iomem *regs;
+	int irq0;	/* MODF irq */
+	int irq1;	/* SPIF irq */
+	int ipb_freq;
+
+	/* Statistics */
+	int msg_count;
+	int wcol_count;
+	int wcol_ticks;
+	u32 wcol_tx_timestamp;
+	int modf_count;
+	int byte_count;
+
+	struct list_head queue;		/* queue of pending messages */
+	spinlock_t lock;
+	struct work_struct work;
+
+
+	/* Details of current transfer (length, and buffer pointers) */
+	struct spi_message *message;	/* current message */
+	struct spi_transfer *transfer;	/* current transfer */
+	int (*state)(int irq, struct mpc52xx_spi *ms, u8 status, u8 data);
+	int len;
+	int timestamp;
+	u8 *rx_buf;
+	const u8 *tx_buf;
+	int cs_change;
+};
+
+/*
+ * CS control function
+ */
+static void mpc52xx_spi_chipsel(struct mpc52xx_spi *ms, int value)
+{
+	out_8(ms->regs + SPI_PORTDATA, value ? 0 : 0x08);
+}
+
+/*
+ * Start a new transfer.  This is called both by the idle state
+ * for the first transfer in a message, and by the wait state when the
+ * previous transfer in a message is complete.
+ */
+static void mpc52xx_spi_start_transfer(struct mpc52xx_spi *ms)
+{
+	ms->rx_buf = ms->transfer->rx_buf;
+	ms->tx_buf = ms->transfer->tx_buf;
+	ms->len = ms->transfer->len;
+
+	/* Activate the chip select */
+	if (ms->cs_change)
+		mpc52xx_spi_chipsel(ms, 1);
+	ms->cs_change = ms->transfer->cs_change;
+
+	/* Write out the first byte */
+	ms->wcol_tx_timestamp = get_tbl();
+	if (ms->tx_buf)
+		out_8(ms->regs + SPI_DATA, *ms->tx_buf++);
+	else
+		out_8(ms->regs + SPI_DATA, 0);
+}
+
+/* Forward declaration of state handlers */
+static int mpc52xx_spi_fsmstate_transfer(int irq, struct mpc52xx_spi *ms,
+					 u8 status, u8 data);
+static int mpc52xx_spi_fsmstate_wait(int irq, struct mpc52xx_spi *ms,
+				     u8 status, u8 data);
+
+/*
+ * IDLE state
+ *
+ * No transfers are in progress; if another transfer is pending then retrieve
+ * it and kick it off.  Otherwise, stop processing the state machine
+ */
+static int
+mpc52xx_spi_fsmstate_idle(int irq, struct mpc52xx_spi *ms, u8 status, u8 data)
+{
+	struct spi_device *spi;
+	int spr, sppr;
+	u8 ctrl1;
+
+	if (status && (irq != NO_IRQ))
+		dev_err(&ms->master->dev, "spurious irq, status=0x%.2x\n",
+			status);
+
+	/* Check if there is another transfer waiting. */
+	if (list_empty(&ms->queue))
+		return FSM_STOP;
+
+	/* get the head of the queue */
+	ms->message = list_first_entry(&ms->queue, struct spi_message, queue);
+	list_del_init(&ms->message->queue);
+
+	/* Setup the controller parameters */
+	ctrl1 = SPI_CTRL1_SPIE | SPI_CTRL1_SPE | SPI_CTRL1_MSTR;
+	spi = ms->message->spi;
+	if (spi->mode & SPI_CPHA)
+		ctrl1 |= SPI_CTRL1_CPHA;
+	if (spi->mode & SPI_CPOL)
+		ctrl1 |= SPI_CTRL1_CPOL;
+	if (spi->mode & SPI_LSB_FIRST)
+		ctrl1 |= SPI_CTRL1_LSBFE;
+	out_8(ms->regs + SPI_CTRL1, ctrl1);
+
+	/* Setup the controller speed */
+	/* minimum divider is '2'.  Also, add '1' to force rounding the
+	 * divider up. */
+	sppr = ((ms->ipb_freq / ms->message->spi->max_speed_hz) + 1) >> 1;
+	spr = 0;
+	if (sppr < 1)
+		sppr = 1;
+	while (((sppr - 1) & ~0x7) != 0) {
+		sppr = (sppr + 1) >> 1; /* add '1' to force rounding up */
+		spr++;
+	}
+	sppr--;		/* sppr quantity in register is offset by 1 */
+	if (spr > 7) {
+		/* Don't overrun limits of SPI baudrate register */
+		spr = 7;
+		sppr = 7;
+	}
+	out_8(ms->regs + SPI_BRR, sppr << 4 | spr); /* Set speed */
+
+	ms->cs_change = 1;
+	ms->transfer = container_of(ms->message->transfers.next,
+				    struct spi_transfer, transfer_list);
+
+	mpc52xx_spi_start_transfer(ms);
+	ms->state = mpc52xx_spi_fsmstate_transfer;
+
+	return FSM_CONTINUE;
+}
+
+/*
+ * TRANSFER state
+ *
+ * In the middle of a transfer.  If the SPI core has completed processing
+ * a byte, then read out the received data and write out the next byte
+ * (unless this transfer is finished; in which case go on to the wait
+ * state)
+ */
+static int mpc52xx_spi_fsmstate_transfer(int irq, struct mpc52xx_spi *ms,
+					 u8 status, u8 data)
+{
+	if (!status)
+		return ms->irq0 ? FSM_STOP : FSM_POLL;
+
+	if (status & SPI_STATUS_WCOL) {
+		/* The SPI controller is stoopid.  At slower speeds, it may
+		 * raise the SPIF flag before the state machine is actually
+		 * finished, which causes a collision (internal to the state
+		 * machine only).  The manual recommends inserting a delay
+		 * between receiving the interrupt and sending the next byte,
+		 * but it can also be worked around simply by retrying the
+		 * transfer which is what we do here. */
+		ms->wcol_count++;
+		ms->wcol_ticks += get_tbl() - ms->wcol_tx_timestamp;
+		ms->wcol_tx_timestamp = get_tbl();
+		data = 0;
+		if (ms->tx_buf)
+			data = *(ms->tx_buf-1);
+		out_8(ms->regs + SPI_DATA, data); /* try again */
+		return FSM_CONTINUE;
+	} else if (status & SPI_STATUS_MODF) {
+		ms->modf_count++;
+		dev_err(&ms->master->dev, "mode fault\n");
+		mpc52xx_spi_chipsel(ms, 0);
+		ms->message->status = -EIO;
+		ms->message->complete(ms->message->context);
+		ms->state = mpc52xx_spi_fsmstate_idle;
+		return FSM_CONTINUE;
+	}
+
+	/* Read data out of the spi device */
+	ms->byte_count++;
+	if (ms->rx_buf)
+		*ms->rx_buf++ = data;
+
+	/* Is the transfer complete? */
+	ms->len--;
+	if (ms->len == 0) {
+		ms->timestamp = get_tbl();
+		ms->timestamp += ms->transfer->delay_usecs * tb_ticks_per_usec;
+		ms->state = mpc52xx_spi_fsmstate_wait;
+		return FSM_CONTINUE;
+	}
+
+	/* Write out the next byte */
+	ms->wcol_tx_timestamp = get_tbl();
+	if (ms->tx_buf)
+		out_8(ms->regs + SPI_DATA, *ms->tx_buf++);
+	else
+		out_8(ms->regs + SPI_DATA, 0);
+
+	return FSM_CONTINUE;
+}
+
+/*
+ * WAIT state
+ *
+ * A transfer has completed; need to wait for the delay period to complete
+ * before starting the next transfer
+ */
+static int
+mpc52xx_spi_fsmstate_wait(int irq, struct mpc52xx_spi *ms, u8 status, u8 data)
+{
+	if (status && irq)
+		dev_err(&ms->master->dev, "spurious irq, status=0x%.2x\n",
+			status);
+
+	if (((int)get_tbl()) - ms->timestamp < 0)
+		return FSM_POLL;
+
+	ms->message->actual_length += ms->transfer->len;
+
+	/* Check if there is another transfer in this message.  If there
+	 * aren't then deactivate CS, notify sender, and drop back to idle
+	 * to start the next message. */
+	if (ms->transfer->transfer_list.next == &ms->message->transfers) {
+		ms->msg_count++;
+		mpc52xx_spi_chipsel(ms, 0);
+		ms->message->status = 0;
+		ms->message->complete(ms->message->context);
+		ms->state = mpc52xx_spi_fsmstate_idle;
+		return FSM_CONTINUE;
+	}
+
+	/* There is another transfer; kick it off */
+
+	if (ms->cs_change)
+		mpc52xx_spi_chipsel(ms, 0);
+
+	ms->transfer = container_of(ms->transfer->transfer_list.next,
+				    struct spi_transfer, transfer_list);
+	mpc52xx_spi_start_transfer(ms);
+	ms->state = mpc52xx_spi_fsmstate_transfer;
+	return FSM_CONTINUE;
+}
+
+/**
+ * mpc52xx_spi_fsm_process - Finite State Machine iteration function
+ * @irq: irq number that triggered the FSM or 0 for polling
+ * @ms: pointer to mpc52xx_spi driver data
+ */
+static void mpc52xx_spi_fsm_process(int irq, struct mpc52xx_spi *ms)
+{
+	int rc = FSM_CONTINUE;
+	u8 status, data;
+
+	while (rc == FSM_CONTINUE) {
+		/* Interrupt cleared by read of STATUS followed by
+		 * read of DATA registers */
+		status = in_8(ms->regs + SPI_STATUS);
+		data = in_8(ms->regs + SPI_DATA);
+		rc = ms->state(irq, ms, status, data);
+	}
+
+	if (rc == FSM_POLL)
+		schedule_work(&ms->work);
+}
+
+/**
+ * mpc52xx_spi_irq - IRQ handler
+ */
+static irqreturn_t mpc52xx_spi_irq(int irq, void *_ms)
+{
+	struct mpc52xx_spi *ms = _ms;
+	spin_lock(&ms->lock);
+	mpc52xx_spi_fsm_process(irq, ms);
+	spin_unlock(&ms->lock);
+	return IRQ_HANDLED;
+}
+
+/**
+ * mpc52xx_spi_wq - Workqueue function for polling the state machine
+ */
+static void mpc52xx_spi_wq(struct work_struct *work)
+{
+	struct mpc52xx_spi *ms = container_of(work, struct mpc52xx_spi, work);
+	unsigned long flags;
+
+	spin_lock_irqsave(&ms->lock, flags);
+	mpc52xx_spi_fsm_process(0, ms);
+	spin_unlock_irqrestore(&ms->lock, flags);
+}
+
+/*
+ * spi_master ops
+ */
+
+static int mpc52xx_spi_setup(struct spi_device *spi)
+{
+	if (spi->bits_per_word % 8)
+		return -EINVAL;
+
+	if (spi->mode & ~(SPI_CPOL | SPI_CPHA | SPI_LSB_FIRST))
+		return -EINVAL;
+
+	if (spi->chip_select >= spi->master->num_chipselect)
+		return -EINVAL;
+
+	return 0;
+}
+
+static int mpc52xx_spi_transfer(struct spi_device *spi, struct spi_message *m)
+{
+	struct mpc52xx_spi *ms = spi_master_get_devdata(spi->master);
+	unsigned long flags;
+
+	m->actual_length = 0;
+	m->status = -EINPROGRESS;
+
+	spin_lock_irqsave(&ms->lock, flags);
+	list_add_tail(&m->queue, &ms->queue);
+	spin_unlock_irqrestore(&ms->lock, flags);
+	schedule_work(&ms->work);
+
+	return 0;
+}
+
+/*
+ * OF Platform Bus Binding
+ */
+static int __devinit mpc52xx_spi_probe(struct of_device *op,
+				       const struct of_device_id *match)
+{
+	struct spi_master *master;
+	struct mpc52xx_spi *ms;
+	void __iomem *regs;
+	int rc;
+
+	/* MMIO registers */
+	dev_dbg(&op->dev, "probing mpc5200 SPI device\n");
+	regs = of_iomap(op->node, 0);
+	if (!regs)
+		return -ENODEV;
+
+	/* initialize the device */
+	out_8(regs+SPI_CTRL1, SPI_CTRL1_SPIE | SPI_CTRL1_SPE | SPI_CTRL1_MSTR);
+	out_8(regs + SPI_CTRL2, 0x0);
+	out_8(regs + SPI_DATADIR, 0xe);	/* Set output pins */
+	out_8(regs + SPI_PORTDATA, 0x8);	/* Deassert /SS signal */
+
+	/* Clear the status register and re-read it to check for a MODF
+	 * failure.  This driver cannot currently handle multiple masters
+	 * on the SPI bus.  This fault will also occur if the SPI signals
+	 * are not connected to any pins (port_config setting) */
+	in_8(regs + SPI_STATUS);
+	in_8(regs + SPI_DATA);
+	if (in_8(regs + SPI_STATUS) & SPI_STATUS_MODF) {
+		dev_err(&op->dev, "mode fault; is port_config correct?\n");
+		rc = -EIO;
+		goto err_init;
+	}
+
+	dev_dbg(&op->dev, "allocating spi_master struct\n");
+	master = spi_alloc_master(&op->dev, sizeof *ms);
+	if (!master) {
+		rc = -ENOMEM;
+		goto err_alloc;
+	}
+	master->bus_num = -1;
+	master->num_chipselect = 1;
+	master->setup = mpc52xx_spi_setup;
+	master->transfer = mpc52xx_spi_transfer;
+	dev_set_drvdata(&op->dev, master);
+
+	ms = spi_master_get_devdata(master);
+	ms->master = master;
+	ms->regs = regs;
+	ms->irq0 = irq_of_parse_and_map(op->node, 0);
+	ms->irq1 = irq_of_parse_and_map(op->node, 1);
+	ms->state = mpc52xx_spi_fsmstate_idle;
+	ms->ipb_freq = mpc5xxx_get_bus_frequency(op->node);
+	spin_lock_init(&ms->lock);
+	INIT_LIST_HEAD(&ms->queue);
+	INIT_WORK(&ms->work, mpc52xx_spi_wq);
+
+	/* Decide if interrupts can be used */
+	if (ms->irq0 && ms->irq1) {
+		rc = request_irq(ms->irq0, mpc52xx_spi_irq, IRQF_SAMPLE_RANDOM,
+				  "mpc5200-spi-modf", ms);
+		rc |= request_irq(ms->irq1, mpc52xx_spi_irq, IRQF_SAMPLE_RANDOM,
+				  "mpc5200-spi-spiF", ms);
+		if (rc) {
+			free_irq(ms->irq0, ms);
+			free_irq(ms->irq1, ms);
+			ms->irq0 = ms->irq1 = 0;
+		}
+	} else {
+		/* operate in polled mode */
+		ms->irq0 = ms->irq1 = 0;
+	}
+
+	if (!ms->irq0)
+		dev_info(&op->dev, "using polled mode\n");
+
+	dev_dbg(&op->dev, "registering spi_master struct\n");
+	rc = spi_register_master(master);
+	if (rc)
+		goto err_register;
+
+	of_register_spi_devices(master, op->node);
+	dev_info(&ms->master->dev, "registered MPC5200 SPI bus\n");
+
+	return rc;
+
+ err_register:
+	dev_err(&ms->master->dev, "initialization failed\n");
+	spi_master_put(master);
+ err_alloc:
+ err_init:
+	iounmap(regs);
+	return rc;
+}
+
+static int __devexit mpc52xx_spi_remove(struct of_device *op)
+{
+	struct spi_master *master = dev_get_drvdata(&op->dev);
+	struct mpc52xx_spi *ms = spi_master_get_devdata(master);
+
+	free_irq(ms->irq0, ms);
+	free_irq(ms->irq1, ms);
+
+	spi_unregister_master(master);
+	spi_master_put(master);
+	iounmap(ms->regs);
+
+	return 0;
+}
+
+static struct of_device_id mpc52xx_spi_match[] __devinitdata = {
+	{ .compatible = "fsl,mpc5200-spi", },
+	{}
+};
+MODULE_DEVICE_TABLE(of, mpc52xx_spi_match);
+
+static struct of_platform_driver mpc52xx_spi_of_driver = {
+	.owner = THIS_MODULE,
+	.name = "mpc52xx-spi",
+	.match_table = mpc52xx_spi_match,
+	.probe = mpc52xx_spi_probe,
+	.remove = __exit_p(mpc52xx_spi_remove),
+};
+
+static int __init mpc52xx_spi_init(void)
+{
+	return of_register_platform_driver(&mpc52xx_spi_of_driver);
+}
+module_init(mpc52xx_spi_init);
+
+static void __exit mpc52xx_spi_exit(void)
+{
+	of_unregister_platform_driver(&mpc52xx_spi_of_driver);
+}
+module_exit(mpc52xx_spi_exit);
+
diff --git a/include/linux/spi/mpc52xx_spi.h b/include/linux/spi/mpc52xx_spi.h
new file mode 100644
index 0000000..d1004cf
--- /dev/null
+++ b/include/linux/spi/mpc52xx_spi.h
@@ -0,0 +1,10 @@
+
+#ifndef INCLUDE_MPC5200_SPI_H
+#define INCLUDE_MPC5200_SPI_H
+
+extern void mpc52xx_spi_set_premessage_hook(struct spi_master *master,
+					    void (*hook)(struct spi_message *m,
+							 void *context),
+					    void *hook_context);
+
+#endif