ramips: add SPI controller driver

Based on a patch by Sergiy <piratfm@gmail.com>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@27809 3c298f89-4303-0410-b956-a3cf2f4a3e73

1 files changed, 558 insertions, 0 deletions

diff --git a/target/linux/ramips/files/drivers/spi/ramips_spi.c b/target/linux/ramips/files/drivers/spi/ramips_spi.c
new file mode 100644
index 000000000..b59b6bb05
--- /dev/null
+++ b/target/linux/ramips/files/drivers/spi/ramips_spi.c
@@ -0,0 +1,558 @@
+/*
+ * ramips_spi.c -- Ralink RT288x/RT305x SPI controller driver
+ *
+ * Copyright (C) 2011 Sergiy <piratfm@gmail.com>
+ * Copyright (C) 2011 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/init.h>
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/delay.h>
+#include <linux/platform_device.h>
+#include <linux/io.h>
+#include <linux/spi/spi.h>
+
+#define DRIVER_NAME			"ramips-spi"
+#define RALINK_NUM_CHIPSELECTS		1 /* only one slave is supported*/
+#define RALINK_SPI_WAIT_RDY_MAX_LOOP	2000 /* in usec */
+
+#define RAMIPS_SPI_STAT			0x00
+#define RAMIPS_SPI_CFG			0x10
+#define RAMIPS_SPI_CTL			0x14
+#define RAMIPS_SPI_DATA			0x20
+
+/* SPISTAT register bit field */
+#define SPISTAT_BUSY			BIT(0)
+
+/* SPICFG register bit field */
+#define SPICFG_LSBFIRST			0
+#define SPICFG_MSBFIRST			BIT(8)
+#define SPICFG_SPICLKPOL		BIT(6)
+#define SPICFG_RXCLKEDGE_FALLING	BIT(5)
+#define SPICFG_TXCLKEDGE_FALLING	BIT(4)
+#define SPICFG_SPICLK_PRESCALE_MASK	0x7
+#define SPICFG_SPICLK_DIV2		0
+#define SPICFG_SPICLK_DIV4		1
+#define SPICFG_SPICLK_DIV8		2
+#define SPICFG_SPICLK_DIV16		3
+#define SPICFG_SPICLK_DIV32		4
+#define SPICFG_SPICLK_DIV64		5
+#define SPICFG_SPICLK_DIV128		6
+#define SPICFG_SPICLK_DISABLE		7
+
+/* SPICTL register bit field */
+#define SPICTL_HIZSDO			BIT(3)
+#define SPICTL_STARTWR			BIT(2)
+#define SPICTL_STARTRD			BIT(1)
+#define SPICTL_SPIENA			BIT(0)
+
+#ifdef DEBUG
+#define spi_debug(args...) printk(args)
+#else
+#define spi_debug(args...)
+#endif
+
+struct ramips_spi {
+	struct work_struct	work;
+
+	/* Lock access to transfer list.*/
+	spinlock_t		lock;
+
+	struct list_head	msg_queue;
+	struct spi_master	*master;
+	void __iomem		*base;
+	unsigned int		sys_freq;
+	unsigned int		speed;
+
+	struct clk		*clk;
+};
+
+static struct workqueue_struct *ramips_spi_wq;
+
+static inline struct ramips_spi *ramips_spidev_to_rs(struct spi_device *spi)
+{
+	return spi_master_get_devdata(spi->master);
+}
+
+static inline u32 ramips_spi_read(struct ramips_spi *rs, u32 reg)
+{
+	return ioread32(rs->base + reg);
+}
+
+static inline void ramips_spi_write(struct ramips_spi *rs, u32 reg, u32 val)
+{
+	iowrite32(val, rs->base + reg);
+}
+
+static inline void ramips_spi_setbits(struct ramips_spi *rs, u32 reg, u32 mask)
+{
+	void __iomem *addr = rs->base + reg;
+	u32 val;
+
+	val = ioread32(addr);
+	val |= mask;
+	iowrite32(val, addr);
+}
+
+static inline void ramips_spi_clrbits(struct ramips_spi *rs, u32 reg, u32 mask)
+{
+	void __iomem *addr = rs->base + reg;
+	u32 val;
+
+	val = ioread32(addr);
+	val &= ~mask;
+	iowrite32(val, addr);
+}
+
+static int ramips_spi_baudrate_set(struct spi_device *spi, unsigned int speed)
+{
+	struct ramips_spi *rs = ramips_spidev_to_rs(spi);
+	u32 rate;
+	u32 prescale;
+	u32 reg;
+
+	spi_debug("%s: speed:%u\n", __func__, speed);
+
+	/*
+	 * the supported rates are: 2,4,8...128
+	 * round up as we look for equal or less speed
+	 */
+	rate = DIV_ROUND_UP(rs->sys_freq, speed);
+	spi_debug("%s: rate-1:%u\n", __func__, rate);
+	rate = roundup_pow_of_two(rate);
+	spi_debug("%s: rate-2:%u\n", __func__, rate);
+
+	/* check if requested speed is too small */
+	if (rate > 128)
+		return -EINVAL;
+
+	if (rate < 2)
+		rate = 2;
+
+	/* Convert the rate to SPI clock divisor value.	*/
+	prescale = ilog2(rate/2);
+	spi_debug("%s: prescale:%u\n", __func__, prescale);
+
+	reg = ramips_spi_read(rs, RAMIPS_SPI_CFG);
+	reg = ((reg & ~SPICFG_SPICLK_PRESCALE_MASK) | prescale);
+	ramips_spi_write(rs, RAMIPS_SPI_CFG, reg);
+	rs->speed = speed;
+	return 0;
+}
+
+/*
+ * called only when no transfer is active on the bus
+ */
+static int
+ramips_spi_setup_transfer(struct spi_device *spi, struct spi_transfer *t)
+{
+	struct ramips_spi *rs = ramips_spidev_to_rs(spi);
+	unsigned int speed = spi->max_speed_hz;
+	int	rc;
+	unsigned int bits_per_word = 8;
+
+	if ((t != NULL) && t->speed_hz)
+		speed = t->speed_hz;
+
+	if ((t != NULL) && t->bits_per_word)
+		bits_per_word = t->bits_per_word;
+
+	if (rs->speed != speed) {
+		spi_debug("%s: speed_hz:%u\n", __func__, speed);
+		rc = ramips_spi_baudrate_set(spi, speed);
+		if (rc)
+			return rc;
+	}
+
+	if (bits_per_word != 8) {
+		spi_debug("%s: bad bits_per_word: %u\n", __func__,
+			  bits_per_word);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static void ramips_spi_set_cs(struct ramips_spi *rs, int enable)
+{
+	if (enable)
+		ramips_spi_clrbits(rs, RAMIPS_SPI_CTL, SPICTL_SPIENA);
+	else
+		ramips_spi_setbits(rs, RAMIPS_SPI_CTL, SPICTL_SPIENA);
+}
+
+static inline int ramips_spi_wait_till_ready(struct ramips_spi *rs)
+{
+	int i;
+
+	for (i = 0; i < RALINK_SPI_WAIT_RDY_MAX_LOOP; i++) {
+		u32 status;
+
+		status = ramips_spi_read(rs, RAMIPS_SPI_STAT);
+		if ((status & SPISTAT_BUSY) == 0)
+			return 0;
+
+		udelay(1);
+	}
+
+	return -ETIMEDOUT;
+}
+
+static unsigned int
+ramips_spi_write_read(struct spi_device *spi, struct spi_transfer *xfer)
+{
+	struct ramips_spi *rs = ramips_spidev_to_rs(spi);
+	unsigned count = 0;
+	u8 *rx = xfer->rx_buf;
+	const u8 *tx = xfer->tx_buf;
+	int err;
+
+	spi_debug("%s(%d): %s %s\n", __func__, xfer->len,
+		  (tx != NULL) ? "tx" : "  ",
+		  (rx != NULL) ? "rx" : "  ");
+
+	if (tx) {
+		for (count = 0; count < xfer->len; count++) {
+			ramips_spi_write(rs, RAMIPS_SPI_DATA, tx[count]);
+			ramips_spi_setbits(rs, RAMIPS_SPI_CTL, SPICTL_STARTWR);
+			err = ramips_spi_wait_till_ready(rs);
+			if (err) {
+				dev_err(&spi->dev, "TX failed, err=%d\n", err);
+				goto out;
+			}
+		}
+	}
+
+	if (rx) {
+		for (count = 0; count < xfer->len; count++) {
+			ramips_spi_setbits(rs, RAMIPS_SPI_CTL, SPICTL_STARTRD);
+			err = ramips_spi_wait_till_ready(rs);
+			if (err) {
+				dev_err(&spi->dev, "RX failed, err=%d\n", err);
+				goto out;
+			}
+			rx[count] = (u8) ramips_spi_read(rs, RAMIPS_SPI_DATA);
+		}
+	}
+
+out:
+	return count;
+}
+
+static void ramips_spi_work(struct work_struct *work)
+{
+	struct ramips_spi *rs =
+		container_of(work, struct ramips_spi, work);
+
+	spin_lock_irq(&rs->lock);
+	while (!list_empty(&rs->msg_queue)) {
+		struct spi_message *m;
+		struct spi_device *spi;
+		struct spi_transfer *t = NULL;
+		int par_override = 0;
+		int status = 0;
+		int cs_active = 0;
+
+		m = container_of(rs->msg_queue.next, struct spi_message,
+				 queue);
+
+		list_del_init(&m->queue);
+		spin_unlock_irq(&rs->lock);
+
+		spi = m->spi;
+
+		/* Load defaults */
+		status = ramips_spi_setup_transfer(spi, NULL);
+
+		if (status < 0)
+			goto msg_done;
+
+		list_for_each_entry(t, &m->transfers, transfer_list) {
+			if (par_override || t->speed_hz || t->bits_per_word) {
+				par_override = 1;
+				status = ramips_spi_setup_transfer(spi, t);
+				if (status < 0)
+					break;
+				if (!t->speed_hz && !t->bits_per_word)
+					par_override = 0;
+			}
+
+			if (!cs_active) {
+				ramips_spi_set_cs(rs, 1);
+				cs_active = 1;
+			}
+
+			if (t->len)
+				m->actual_length +=
+					ramips_spi_write_read(spi, t);
+
+			if (t->delay_usecs)
+				udelay(t->delay_usecs);
+
+			if (t->cs_change) {
+				ramips_spi_set_cs(rs, 0);
+				cs_active = 0;
+			}
+		}
+
+msg_done:
+		if (cs_active)
+			ramips_spi_set_cs(rs, 0);
+
+		m->status = status;
+		m->complete(m->context);
+
+		spin_lock_irq(&rs->lock);
+	}
+
+	spin_unlock_irq(&rs->lock);
+}
+
+static int ramips_spi_setup(struct spi_device *spi)
+{
+	struct ramips_spi *rs = ramips_spidev_to_rs(spi);
+
+	if ((spi->max_speed_hz == 0) ||
+	    (spi->max_speed_hz > (rs->sys_freq / 2)))
+		spi->max_speed_hz = (rs->sys_freq / 2);
+
+	if (spi->max_speed_hz < (rs->sys_freq/128)) {
+		dev_err(&spi->dev, "setup: requested speed too low %d Hz\n",
+			spi->max_speed_hz);
+		return -EINVAL;
+	}
+
+	if (spi->bits_per_word != 0 && spi->bits_per_word != 8) {
+		dev_err(&spi->dev,
+			"setup: requested bits per words - os wrong %d bpw\n",
+			spi->bits_per_word);
+		return -EINVAL;
+	}
+
+	if (spi->bits_per_word == 0)
+		spi->bits_per_word = 8;
+
+	/*
+	 * baudrate & width will be set ramips_spi_setup_transfer
+	 */
+	return 0;
+}
+
+static int ramips_spi_transfer(struct spi_device *spi, struct spi_message *m)
+{
+	struct ramips_spi *rs;
+	struct spi_transfer *t = NULL;
+	unsigned long flags;
+
+	m->actual_length = 0;
+	m->status = 0;
+
+	/* reject invalid messages and transfers */
+	if (list_empty(&m->transfers) || !m->complete)
+		return -EINVAL;
+
+	rs = ramips_spidev_to_rs(spi);
+
+	list_for_each_entry(t, &m->transfers, transfer_list) {
+		unsigned int bits_per_word = spi->bits_per_word;
+
+		if (t->tx_buf == NULL && t->rx_buf == NULL && t->len) {
+			dev_err(&spi->dev,
+				"message rejected : "
+				"invalid transfer data buffers\n");
+			goto msg_rejected;
+		}
+
+		if (t->bits_per_word)
+			bits_per_word = t->bits_per_word;
+
+		if (bits_per_word != 8) {
+			dev_err(&spi->dev,
+				"message rejected : "
+				"invalid transfer bits_per_word (%d bits)\n",
+				bits_per_word);
+			goto msg_rejected;
+		}
+
+		if (t->speed_hz && t->speed_hz < (rs->sys_freq/128)) {
+			dev_err(&spi->dev,
+				"message rejected : "
+				"device min speed (%d Hz) exceeds "
+				"required transfer speed (%d Hz)\n",
+				(rs->sys_freq/128), t->speed_hz);
+			goto msg_rejected;
+		}
+	}
+
+
+	spin_lock_irqsave(&rs->lock, flags);
+	list_add_tail(&m->queue, &rs->msg_queue);
+	queue_work(ramips_spi_wq, &rs->work);
+	spin_unlock_irqrestore(&rs->lock, flags);
+
+	return 0;
+msg_rejected:
+	/* Message rejected and not queued */
+	m->status = -EINVAL;
+	if (m->complete)
+		m->complete(m->context);
+	return -EINVAL;
+}
+
+static void __init ramips_spi_reset(struct ramips_spi *rs)
+{
+	ramips_spi_write(rs, RAMIPS_SPI_CFG,
+			 SPICFG_MSBFIRST | SPICFG_TXCLKEDGE_FALLING |
+			 SPICFG_SPICLK_DIV16 | SPICFG_SPICLKPOL);
+	ramips_spi_write(rs, RAMIPS_SPI_CTL, SPICTL_HIZSDO | SPICTL_SPIENA);
+}
+
+static int __init ramips_spi_probe(struct platform_device *pdev)
+{
+	struct spi_master *master;
+	struct ramips_spi *rs;
+	struct resource *r;
+	int status = 0;
+
+	master = spi_alloc_master(&pdev->dev, sizeof(*rs));
+	if (master == NULL) {
+		dev_dbg(&pdev->dev, "master allocation failed\n");
+		return -ENOMEM;
+	}
+
+	if (pdev->id != -1)
+		master->bus_num = pdev->id;
+
+	/* we support only mode 0, and no options */
+	master->mode_bits = 0;
+
+	master->setup = ramips_spi_setup;
+	master->transfer = ramips_spi_transfer;
+	master->num_chipselect = RALINK_NUM_CHIPSELECTS;
+
+	dev_set_drvdata(&pdev->dev, master);
+
+	rs = spi_master_get_devdata(master);
+	rs->master = master;
+
+	rs->clk = clk_get(NULL, "sys");
+	if (IS_ERR(rs->clk)) {
+		status = PTR_ERR(rs->clk);
+		dev_err(&pdev->dev, "unable to get SYS clock, err=%d\n",
+			status);
+		goto out_put_master;
+	}
+
+	status = clk_enable(rs->clk);
+	if (status)
+		goto out_put_clk;
+
+	rs->sys_freq = clk_get_rate(rs->clk);
+	spi_debug("%s: sys_freq: %ld\n", __func__, rs->sys_freq);
+
+	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (r == NULL) {
+		status = -ENODEV;
+		goto out_disable_clk;
+	}
+
+	if (!request_mem_region(r->start, (r->end - r->start) + 1,
+				dev_name(&pdev->dev))) {
+		status = -EBUSY;
+		goto out_disable_clk;
+	}
+
+	rs->base = ioremap(r->start, resource_size(r));
+	if (rs->base == NULL) {
+		dev_err(&pdev->dev, "ioremap failed\n");
+		status = -ENOMEM;
+		goto out_rel_mem;
+	}
+
+	INIT_WORK(&rs->work, ramips_spi_work);
+
+	spin_lock_init(&rs->lock);
+	INIT_LIST_HEAD(&rs->msg_queue);
+
+	ramips_spi_reset(rs);
+
+	status = spi_register_master(master);
+	if (status)
+		goto out_unmap_base;
+
+	return 0;
+
+out_unmap_base:
+	iounmap(rs->base);
+out_rel_mem:
+	release_mem_region(r->start, (r->end - r->start) + 1);
+out_disable_clk:
+	clk_disable(rs->clk);
+out_put_clk:
+	clk_put(rs->clk);
+out_put_master:
+	spi_master_put(master);
+	return status;
+}
+
+static int __devexit ramips_spi_remove(struct platform_device *pdev)
+{
+	struct spi_master *master;
+	struct ramips_spi *rs;
+	struct resource *r;
+
+	master = dev_get_drvdata(&pdev->dev);
+	rs = spi_master_get_devdata(master);
+
+	cancel_work_sync(&rs->work);
+
+	iounmap(rs->base);
+	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	release_mem_region(r->start, (r->end - r->start) + 1);
+
+	clk_disable(rs->clk);
+	clk_put(rs->clk);
+	spi_unregister_master(master);
+
+	return 0;
+}
+
+MODULE_ALIAS("platform:" DRIVER_NAME);
+
+static struct platform_driver ramips_spi_driver = {
+	.driver = {
+		.name	= DRIVER_NAME,
+		.owner	= THIS_MODULE,
+	},
+	.remove		= __devexit_p(ramips_spi_remove),
+};
+
+static int __init ramips_spi_init(void)
+{
+	ramips_spi_wq = create_singlethread_workqueue(
+				ramips_spi_driver.driver.name);
+	if (ramips_spi_wq == NULL)
+		return -ENOMEM;
+
+	return platform_driver_probe(&ramips_spi_driver, ramips_spi_probe);
+}
+module_init(ramips_spi_init);
+
+static void __exit ramips_spi_exit(void)
+{
+	flush_workqueue(ramips_spi_wq);
+	platform_driver_unregister(&ramips_spi_driver);
+
+	destroy_workqueue(ramips_spi_wq);
+}
+module_exit(ramips_spi_exit);
+
+MODULE_DESCRIPTION("Ralink SPI driver");
+MODULE_AUTHOR("Sergiy <piratfm@gmail.com>");
+MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>");
+MODULE_LICENSE("GPL");