--- /dev/null
+/*
+ * 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");
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