spi: new orion_spi driver

This adds an SPI driver for the SPI controller found in various Marvell
Orion ARM SoCs.  It currently supports only one slave, which must use SPI
mode 0.

[dbrownell@users.sourceforge.net: cleanups, meet specs, pass "sparse"]
Signed-off-by: Shadi Ammouri <shadi@marvell.com>
Signed-off-by: Saeed Bishara <saeed@marvell.com>
Signed-off-by: Lennert Buytenhek <buytenh@marvell.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 574 insertions, 0 deletions

diff --git a/drivers/spi/orion_spi.c b/drivers/spi/orion_spi.c
new file mode 100644
index 000000000000..c4eaacd6e553
--- /dev/null
+++ b/drivers/spi/orion_spi.c
@@ -0,0 +1,574 @@
+/*
+ * orion_spi.c -- Marvell Orion SPI controller driver
+ *
+ * Author: Shadi Ammouri <shadi@marvell.com>
+ * Copyright (C) 2007-2008 Marvell Ltd.
+ *
+ * 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/interrupt.h>
+#include <linux/delay.h>
+#include <linux/platform_device.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/spi/spi.h>
+#include <linux/spi/orion_spi.h>
+#include <asm/unaligned.h>
+
+#define DRIVER_NAME                     "orion_spi"
+
+#define ORION_NUM_CHIPSELECTS           1 /* only one slave is supported*/
+#define ORION_SPI_WAIT_RDY_MAX_LOOP     2000 /* in usec */
+
+#define ORION_SPI_IF_CTRL_REG           0x00
+#define ORION_SPI_IF_CONFIG_REG         0x04
+#define ORION_SPI_DATA_OUT_REG          0x08
+#define ORION_SPI_DATA_IN_REG           0x0c
+#define ORION_SPI_INT_CAUSE_REG         0x10
+
+#define ORION_SPI_IF_8_16_BIT_MODE      (1 << 5)
+#define ORION_SPI_CLK_PRESCALE_MASK     0x1F
+
+struct orion_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            max_speed;
+        unsigned int            min_speed;
+        struct orion_spi_info   *spi_info;
+};
+
+static struct workqueue_struct *orion_spi_wq;
+
+static inline void __iomem *spi_reg(struct orion_spi *orion_spi, u32 reg)
+{
+        return orion_spi->base + reg;
+}
+
+static inline void
+orion_spi_setbits(struct orion_spi *orion_spi, u32 reg, u32 mask)
+{
+        void __iomem *reg_addr = spi_reg(orion_spi, reg);
+        u32 val;
+
+        val = readl(reg_addr);
+        val |= mask;
+        writel(val, reg_addr);
+}
+
+static inline void
+orion_spi_clrbits(struct orion_spi *orion_spi, u32 reg, u32 mask)
+{
+        void __iomem *reg_addr = spi_reg(orion_spi, reg);
+        u32 val;
+
+        val = readl(reg_addr);
+        val &= ~mask;
+        writel(val, reg_addr);
+}
+
+static int orion_spi_set_transfer_size(struct orion_spi *orion_spi, int size)
+{
+        if (size == 16) {
+                orion_spi_setbits(orion_spi, ORION_SPI_IF_CONFIG_REG,
+                                  ORION_SPI_IF_8_16_BIT_MODE);
+        } else if (size == 8) {
+                orion_spi_clrbits(orion_spi, ORION_SPI_IF_CONFIG_REG,
+                                  ORION_SPI_IF_8_16_BIT_MODE);
+        } else {
+                pr_debug("Bad bits per word value %d (only 8 or 16 are "
+                         "allowed).\n", size);
+                return -EINVAL;
+        }
+
+        return 0;
+}
+
+static int orion_spi_baudrate_set(struct spi_device *spi, unsigned int speed)
+{
+        u32 tclk_hz;
+        u32 rate;
+        u32 prescale;
+        u32 reg;
+        struct orion_spi *orion_spi;
+
+        orion_spi = spi_master_get_devdata(spi->master);
+
+        tclk_hz = orion_spi->spi_info->tclk;
+
+        /*
+         * the supported rates are: 4,6,8...30
+         * round up as we look for equal or less speed
+         */
+        rate = DIV_ROUND_UP(tclk_hz, speed);
+        rate = roundup(rate, 2);
+
+        /* check if requested speed is too small */
+        if (rate > 30)
+                return -EINVAL;
+
+        if (rate < 4)
+                rate = 4;
+
+        /* Convert the rate to SPI clock divisor value. */
+        prescale = 0x10 + rate/2;
+
+        reg = readl(spi_reg(orion_spi, ORION_SPI_IF_CONFIG_REG));
+        reg = ((reg & ~ORION_SPI_CLK_PRESCALE_MASK) | prescale);
+        writel(reg, spi_reg(orion_spi, ORION_SPI_IF_CONFIG_REG));
+
+        return 0;
+}
+
+/*
+ * called only when no transfer is active on the bus
+ */
+static int
+orion_spi_setup_transfer(struct spi_device *spi, struct spi_transfer *t)
+{
+        struct orion_spi *orion_spi;
+        unsigned int speed = spi->max_speed_hz;
+        unsigned int bits_per_word = spi->bits_per_word;
+        int     rc;
+
+        orion_spi = spi_master_get_devdata(spi->master);
+
+        if ((t != NULL) && t->speed_hz)
+                speed = t->speed_hz;
+
+        if ((t != NULL) && t->bits_per_word)
+                bits_per_word = t->bits_per_word;
+
+        rc = orion_spi_baudrate_set(spi, speed);
+        if (rc)
+                return rc;
+
+        return orion_spi_set_transfer_size(orion_spi, bits_per_word);
+}
+
+static void orion_spi_set_cs(struct orion_spi *orion_spi, int enable)
+{
+        if (enable)
+                orion_spi_setbits(orion_spi, ORION_SPI_IF_CTRL_REG, 0x1);
+        else
+                orion_spi_clrbits(orion_spi, ORION_SPI_IF_CTRL_REG, 0x1);
+}
+
+static inline int orion_spi_wait_till_ready(struct orion_spi *orion_spi)
+{
+        int i;
+
+        for (i = 0; i < ORION_SPI_WAIT_RDY_MAX_LOOP; i++) {
+                if (readl(spi_reg(orion_spi, ORION_SPI_INT_CAUSE_REG)))
+                        return 1;
+                else
+                        udelay(1);
+        }
+
+        return -1;
+}
+
+static inline int
+orion_spi_write_read_8bit(struct spi_device *spi,
+                          const u8 **tx_buf, u8 **rx_buf)
+{
+        void __iomem *tx_reg, *rx_reg, *int_reg;
+        struct orion_spi *orion_spi;
+
+        orion_spi = spi_master_get_devdata(spi->master);
+        tx_reg = spi_reg(orion_spi, ORION_SPI_DATA_OUT_REG);
+        rx_reg = spi_reg(orion_spi, ORION_SPI_DATA_IN_REG);
+        int_reg = spi_reg(orion_spi, ORION_SPI_INT_CAUSE_REG);
+
+        /* clear the interrupt cause register */
+        writel(0x0, int_reg);
+
+        if (tx_buf && *tx_buf)
+                writel(*(*tx_buf)++, tx_reg);
+        else
+                writel(0, tx_reg);
+
+        if (orion_spi_wait_till_ready(orion_spi) < 0) {
+                dev_err(&spi->dev, "TXS timed out\n");
+                return -1;
+        }
+
+        if (rx_buf && *rx_buf)
+                *(*rx_buf)++ = readl(rx_reg);
+
+        return 1;
+}
+
+static inline int
+orion_spi_write_read_16bit(struct spi_device *spi,
+                           const u16 **tx_buf, u16 **rx_buf)
+{
+        void __iomem *tx_reg, *rx_reg, *int_reg;
+        struct orion_spi *orion_spi;
+
+        orion_spi = spi_master_get_devdata(spi->master);
+        tx_reg = spi_reg(orion_spi, ORION_SPI_DATA_OUT_REG);
+        rx_reg = spi_reg(orion_spi, ORION_SPI_DATA_IN_REG);
+        int_reg = spi_reg(orion_spi, ORION_SPI_INT_CAUSE_REG);
+
+        /* clear the interrupt cause register */
+        writel(0x0, int_reg);
+
+        if (tx_buf && *tx_buf)
+                writel(__cpu_to_le16(get_unaligned((*tx_buf)++)), tx_reg);
+        else
+                writel(0, tx_reg);
+
+        if (orion_spi_wait_till_ready(orion_spi) < 0) {
+                dev_err(&spi->dev, "TXS timed out\n");
+                return -1;
+        }
+
+        if (rx_buf && *rx_buf)
+                put_unaligned(__le16_to_cpu(readl(rx_reg)), (*rx_buf)++);
+
+        return 1;
+}
+
+static unsigned int
+orion_spi_write_read(struct spi_device *spi, struct spi_transfer *xfer)
+{
+        struct orion_spi *orion_spi;
+        unsigned int count;
+        int word_len;
+
+        orion_spi = spi_master_get_devdata(spi->master);
+        word_len = spi->bits_per_word;
+        count = xfer->len;
+
+        if (word_len == 8) {
+                const u8 *tx = xfer->tx_buf;
+                u8 *rx = xfer->rx_buf;
+
+                do {
+                        if (orion_spi_write_read_8bit(spi, &tx, &rx) < 0)
+                                goto out;
+                        count--;
+                } while (count);
+        } else if (word_len == 16) {
+                const u16 *tx = xfer->tx_buf;
+                u16 *rx = xfer->rx_buf;
+
+                do {
+                        if (orion_spi_write_read_16bit(spi, &tx, &rx) < 0)
+                                goto out;
+                        count -= 2;
+                } while (count);
+        }
+
+out:
+        return xfer->len - count;
+}
+
+
+static void orion_spi_work(struct work_struct *work)
+{
+        struct orion_spi *orion_spi =
+                container_of(work, struct orion_spi, work);
+
+        spin_lock_irq(&orion_spi->lock);
+        while (!list_empty(&orion_spi->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(orion_spi->msg_queue.next, struct spi_message,
+                                 queue);
+
+                list_del_init(&m->queue);
+                spin_unlock_irq(&orion_spi->lock);
+
+                spi = m->spi;
+
+                /* Load defaults */
+                status = orion_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 = orion_spi_setup_transfer(spi, t);
+                                if (status < 0)
+                                        break;
+                                if (!t->speed_hz && !t->bits_per_word)
+                                        par_override = 0;
+                        }
+
+                        if (!cs_active) {
+                                orion_spi_set_cs(orion_spi, 1);
+                                cs_active = 1;
+                        }
+
+                        if (t->len)
+                                m->actual_length +=
+                                        orion_spi_write_read(spi, t);
+
+                        if (t->delay_usecs)
+                                udelay(t->delay_usecs);
+
+                        if (t->cs_change) {
+                                orion_spi_set_cs(orion_spi, 0);
+                                cs_active = 0;
+                        }
+                }
+
+msg_done:
+                if (cs_active)
+                        orion_spi_set_cs(orion_spi, 0);
+
+                m->status = status;
+                m->complete(m->context);
+
+                spin_lock_irq(&orion_spi->lock);
+        }
+
+        spin_unlock_irq(&orion_spi->lock);
+}
+
+static int __init orion_spi_reset(struct orion_spi *orion_spi)
+{
+        /* Verify that the CS is deasserted */
+        orion_spi_set_cs(orion_spi, 0);
+
+        return 0;
+}
+
+static int orion_spi_setup(struct spi_device *spi)
+{
+        struct orion_spi *orion_spi;
+
+        orion_spi = spi_master_get_devdata(spi->master);
+
+        if (spi->mode) {
+                dev_err(&spi->dev, "setup: unsupported mode bits %x\n",
+                        spi->mode);
+                return -EINVAL;
+        }
+
+        if (spi->bits_per_word == 0)
+                spi->bits_per_word = 8;
+
+        if ((spi->max_speed_hz == 0)
+                        || (spi->max_speed_hz > orion_spi->max_speed))
+                spi->max_speed_hz = orion_spi->max_speed;
+
+        if (spi->max_speed_hz < orion_spi->min_speed) {
+                dev_err(&spi->dev, "setup: requested speed too low %d Hz\n",
+                        spi->max_speed_hz);
+                return -EINVAL;
+        }
+
+        /*
+         * baudrate & width will be set orion_spi_setup_transfer
+         */
+        return 0;
+}
+
+static int orion_spi_transfer(struct spi_device *spi, struct spi_message *m)
+{
+        struct orion_spi *orion_spi;
+        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;
+
+        orion_spi = spi_master_get_devdata(spi->master);
+
+        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 != NULL) && t->bits_per_word)
+                        bits_per_word = t->bits_per_word;
+
+                if ((bits_per_word != 8) && (bits_per_word != 16)) {
+                        dev_err(&spi->dev,
+                                "message rejected : "
+                                "invalid transfer bits_per_word (%d bits)\n",
+                                bits_per_word);
+                        goto msg_rejected;
+                }
+                /*make sure buffer length is even when working in 16 bit mode*/
+                if ((t != NULL) && (t->bits_per_word == 16) && (t->len & 1)) {
+                        dev_err(&spi->dev,
+                                "message rejected : "
+                                "odd data length (%d) while in 16 bit mode\n",
+                                t->len);
+                        goto msg_rejected;
+                }
+
+                if (t->speed_hz < orion_spi->min_speed) {
+                        dev_err(&spi->dev,
+                                "message rejected : "
+                                "device min speed (%d Hz) exceeds "
+                                "required transfer speed (%d Hz)\n",
+                                orion_spi->min_speed, t->speed_hz);
+                        goto msg_rejected;
+                }
+        }
+
+
+        spin_lock_irqsave(&orion_spi->lock, flags);
+        list_add_tail(&m->queue, &orion_spi->msg_queue);
+        queue_work(orion_spi_wq, &orion_spi->work);
+        spin_unlock_irqrestore(&orion_spi->lock, flags);
+
+        return 0;
+msg_rejected:
+        /* Message rejected and not queued */
+        m->status = -EINVAL;
+        if (m->complete)
+                m->complete(m->context);
+        return -EINVAL;
+}
+
+static int __init orion_spi_probe(struct platform_device *pdev)
+{
+        struct spi_master *master;
+        struct orion_spi *spi;
+        struct resource *r;
+        struct orion_spi_info *spi_info;
+        int status = 0;
+
+        spi_info = pdev->dev.platform_data;
+
+        master = spi_alloc_master(&pdev->dev, sizeof *spi);
+        if (master == NULL) {
+                dev_dbg(&pdev->dev, "master allocation failed\n");
+                return -ENOMEM;
+        }
+
+        if (pdev->id != -1)
+                master->bus_num = pdev->id;
+
+        master->setup = orion_spi_setup;
+        master->transfer = orion_spi_transfer;
+        master->num_chipselect = ORION_NUM_CHIPSELECTS;
+
+        dev_set_drvdata(&pdev->dev, master);
+
+        spi = spi_master_get_devdata(master);
+        spi->master = master;
+        spi->spi_info = spi_info;
+
+        spi->max_speed = DIV_ROUND_UP(spi_info->tclk, 4);
+        spi->min_speed = DIV_ROUND_UP(spi_info->tclk, 30);
+
+        r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+        if (r == NULL) {
+                status = -ENODEV;
+                goto out;
+        }
+
+        if (!request_mem_region(r->start, (r->end - r->start) + 1,
+                                pdev->dev.bus_id)) {
+                status = -EBUSY;
+                goto out;
+        }
+        spi->base = ioremap(r->start, SZ_1K);
+
+        INIT_WORK(&spi->work, orion_spi_work);
+
+        spin_lock_init(&spi->lock);
+        INIT_LIST_HEAD(&spi->msg_queue);
+
+        if (orion_spi_reset(spi) < 0)
+                goto out_rel_mem;
+
+        status = spi_register_master(master);
+        if (status < 0)
+                goto out_rel_mem;
+
+        return status;
+
+out_rel_mem:
+        release_mem_region(r->start, (r->end - r->start) + 1);
+
+out:
+        spi_master_put(master);
+        return status;
+}
+
+
+static int __exit orion_spi_remove(struct platform_device *pdev)
+{
+        struct spi_master *master;
+        struct orion_spi *spi;
+        struct resource *r;
+
+        master = dev_get_drvdata(&pdev->dev);
+        spi = spi_master_get_devdata(master);
+
+        cancel_work_sync(&spi->work);
+
+        r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+        release_mem_region(r->start, (r->end - r->start) + 1);
+
+        spi_unregister_master(master);
+
+        return 0;
+}
+
+MODULE_ALIAS("platform:" DRIVER_NAME);
+
+static struct platform_driver orion_spi_driver = {
+        .driver = {
+                .name   = DRIVER_NAME,
+                .owner  = THIS_MODULE,
+        },
+        .remove         = __exit_p(orion_spi_remove),
+};
+
+static int __init orion_spi_init(void)
+{
+        orion_spi_wq = create_singlethread_workqueue(
+                                orion_spi_driver.driver.name);
+        if (orion_spi_wq == NULL)
+                return -ENOMEM;
+
+        return platform_driver_probe(&orion_spi_driver, orion_spi_probe);
+}
+module_init(orion_spi_init);
+
+static void __exit orion_spi_exit(void)
+{
+        flush_workqueue(orion_spi_wq);
+        platform_driver_unregister(&orion_spi_driver);
+
+        destroy_workqueue(orion_spi_wq);
+}
+module_exit(orion_spi_exit);
+
+MODULE_DESCRIPTION("Orion SPI driver");
+MODULE_AUTHOR("Shadi Ammouri <shadi@marvell.com>");
+MODULE_LICENSE("GPL");