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Diffstat (limited to 'drivers/spi/atmel_spi.c')
-rw-r--r--drivers/spi/atmel_spi.c678
1 files changed, 678 insertions, 0 deletions
diff --git a/drivers/spi/atmel_spi.c b/drivers/spi/atmel_spi.c
new file mode 100644
index 00000000000..c2a9fef58ed
--- /dev/null
+++ b/drivers/spi/atmel_spi.c
@@ -0,0 +1,678 @@
+/*
+ * Driver for Atmel AT32 and AT91 SPI Controllers
+ *
+ * Copyright (C) 2006 Atmel Corporation
+ *
+ * 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/kernel.h>
+#include <linux/init.h>
+#include <linux/clk.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/delay.h>
+#include <linux/dma-mapping.h>
+#include <linux/err.h>
+#include <linux/interrupt.h>
+#include <linux/spi/spi.h>
+
+#include <asm/io.h>
+#include <asm/arch/board.h>
+#include <asm/arch/gpio.h>
+
+#include "atmel_spi.h"
+
+/*
+ * The core SPI transfer engine just talks to a register bank to set up
+ * DMA transfers; transfer queue progress is driven by IRQs. The clock
+ * framework provides the base clock, subdivided for each spi_device.
+ *
+ * Newer controllers, marked with "new_1" flag, have:
+ * - CR.LASTXFER
+ * - SPI_MR.DIV32 may become FDIV or must-be-zero (here: always zero)
+ * - SPI_SR.TXEMPTY, SPI_SR.NSSR (and corresponding irqs)
+ * - SPI_CSRx.CSAAT
+ * - SPI_CSRx.SBCR allows faster clocking
+ */
+struct atmel_spi {
+ spinlock_t lock;
+
+ void __iomem *regs;
+ int irq;
+ struct clk *clk;
+ struct platform_device *pdev;
+ unsigned new_1:1;
+
+ u8 stopping;
+ struct list_head queue;
+ struct spi_transfer *current_transfer;
+ unsigned long remaining_bytes;
+
+ void *buffer;
+ dma_addr_t buffer_dma;
+};
+
+#define BUFFER_SIZE PAGE_SIZE
+#define INVALID_DMA_ADDRESS 0xffffffff
+
+/*
+ * Earlier SPI controllers (e.g. on at91rm9200) have a design bug whereby
+ * they assume that spi slave device state will not change on deselect, so
+ * that automagic deselection is OK. Not so! Workaround uses nCSx pins
+ * as GPIOs; or newer controllers have CSAAT and friends.
+ *
+ * Since the CSAAT functionality is a bit weird on newer controllers
+ * as well, we use GPIO to control nCSx pins on all controllers.
+ */
+
+static inline void cs_activate(struct spi_device *spi)
+{
+ unsigned gpio = (unsigned) spi->controller_data;
+ unsigned active = spi->mode & SPI_CS_HIGH;
+
+ dev_dbg(&spi->dev, "activate %u%s\n", gpio, active ? " (high)" : "");
+ gpio_set_value(gpio, active);
+}
+
+static inline void cs_deactivate(struct spi_device *spi)
+{
+ unsigned gpio = (unsigned) spi->controller_data;
+ unsigned active = spi->mode & SPI_CS_HIGH;
+
+ dev_dbg(&spi->dev, "DEactivate %u%s\n", gpio, active ? " (low)" : "");
+ gpio_set_value(gpio, !active);
+}
+
+/*
+ * Submit next transfer for DMA.
+ * lock is held, spi irq is blocked
+ */
+static void atmel_spi_next_xfer(struct spi_master *master,
+ struct spi_message *msg)
+{
+ struct atmel_spi *as = spi_master_get_devdata(master);
+ struct spi_transfer *xfer;
+ u32 len;
+ dma_addr_t tx_dma, rx_dma;
+
+ xfer = as->current_transfer;
+ if (!xfer || as->remaining_bytes == 0) {
+ if (xfer)
+ xfer = list_entry(xfer->transfer_list.next,
+ struct spi_transfer, transfer_list);
+ else
+ xfer = list_entry(msg->transfers.next,
+ struct spi_transfer, transfer_list);
+ as->remaining_bytes = xfer->len;
+ as->current_transfer = xfer;
+ }
+
+ len = as->remaining_bytes;
+
+ tx_dma = xfer->tx_dma;
+ rx_dma = xfer->rx_dma;
+
+ /* use scratch buffer only when rx or tx data is unspecified */
+ if (rx_dma == INVALID_DMA_ADDRESS) {
+ rx_dma = as->buffer_dma;
+ if (len > BUFFER_SIZE)
+ len = BUFFER_SIZE;
+ }
+ if (tx_dma == INVALID_DMA_ADDRESS) {
+ tx_dma = as->buffer_dma;
+ if (len > BUFFER_SIZE)
+ len = BUFFER_SIZE;
+ memset(as->buffer, 0, len);
+ dma_sync_single_for_device(&as->pdev->dev,
+ as->buffer_dma, len, DMA_TO_DEVICE);
+ }
+
+ spi_writel(as, RPR, rx_dma);
+ spi_writel(as, TPR, tx_dma);
+
+ as->remaining_bytes -= len;
+ if (msg->spi->bits_per_word > 8)
+ len >>= 1;
+
+ /* REVISIT: when xfer->delay_usecs == 0, the PDC "next transfer"
+ * mechanism might help avoid the IRQ latency between transfers
+ *
+ * We're also waiting for ENDRX before we start the next
+ * transfer because we need to handle some difficult timing
+ * issues otherwise. If we wait for ENDTX in one transfer and
+ * then starts waiting for ENDRX in the next, it's difficult
+ * to tell the difference between the ENDRX interrupt we're
+ * actually waiting for and the ENDRX interrupt of the
+ * previous transfer.
+ *
+ * It should be doable, though. Just not now...
+ */
+ spi_writel(as, TNCR, 0);
+ spi_writel(as, RNCR, 0);
+ spi_writel(as, IER, SPI_BIT(ENDRX) | SPI_BIT(OVRES));
+
+ dev_dbg(&msg->spi->dev,
+ " start xfer %p: len %u tx %p/%08x rx %p/%08x imr %03x\n",
+ xfer, xfer->len, xfer->tx_buf, xfer->tx_dma,
+ xfer->rx_buf, xfer->rx_dma, spi_readl(as, IMR));
+
+ spi_writel(as, TCR, len);
+ spi_writel(as, RCR, len);
+ spi_writel(as, PTCR, SPI_BIT(TXTEN) | SPI_BIT(RXTEN));
+}
+
+static void atmel_spi_next_message(struct spi_master *master)
+{
+ struct atmel_spi *as = spi_master_get_devdata(master);
+ struct spi_message *msg;
+ u32 mr;
+
+ BUG_ON(as->current_transfer);
+
+ msg = list_entry(as->queue.next, struct spi_message, queue);
+
+ /* Select the chip */
+ mr = spi_readl(as, MR);
+ mr = SPI_BFINS(PCS, ~(1 << msg->spi->chip_select), mr);
+ spi_writel(as, MR, mr);
+ cs_activate(msg->spi);
+
+ atmel_spi_next_xfer(master, msg);
+}
+
+static void
+atmel_spi_dma_map_xfer(struct atmel_spi *as, struct spi_transfer *xfer)
+{
+ xfer->tx_dma = xfer->rx_dma = INVALID_DMA_ADDRESS;
+ if (xfer->tx_buf)
+ xfer->tx_dma = dma_map_single(&as->pdev->dev,
+ (void *) xfer->tx_buf, xfer->len,
+ DMA_TO_DEVICE);
+ if (xfer->rx_buf)
+ xfer->rx_dma = dma_map_single(&as->pdev->dev,
+ xfer->rx_buf, xfer->len,
+ DMA_FROM_DEVICE);
+}
+
+static void atmel_spi_dma_unmap_xfer(struct spi_master *master,
+ struct spi_transfer *xfer)
+{
+ if (xfer->tx_dma != INVALID_DMA_ADDRESS)
+ dma_unmap_single(master->cdev.dev, xfer->tx_dma,
+ xfer->len, DMA_TO_DEVICE);
+ if (xfer->rx_dma != INVALID_DMA_ADDRESS)
+ dma_unmap_single(master->cdev.dev, xfer->rx_dma,
+ xfer->len, DMA_FROM_DEVICE);
+}
+
+static void
+atmel_spi_msg_done(struct spi_master *master, struct atmel_spi *as,
+ struct spi_message *msg, int status)
+{
+ cs_deactivate(msg->spi);
+ list_del(&msg->queue);
+ msg->status = status;
+
+ dev_dbg(master->cdev.dev,
+ "xfer complete: %u bytes transferred\n",
+ msg->actual_length);
+
+ spin_unlock(&as->lock);
+ msg->complete(msg->context);
+ spin_lock(&as->lock);
+
+ as->current_transfer = NULL;
+
+ /* continue if needed */
+ if (list_empty(&as->queue) || as->stopping)
+ spi_writel(as, PTCR, SPI_BIT(RXTDIS) | SPI_BIT(TXTDIS));
+ else
+ atmel_spi_next_message(master);
+}
+
+static irqreturn_t
+atmel_spi_interrupt(int irq, void *dev_id)
+{
+ struct spi_master *master = dev_id;
+ struct atmel_spi *as = spi_master_get_devdata(master);
+ struct spi_message *msg;
+ struct spi_transfer *xfer;
+ u32 status, pending, imr;
+ int ret = IRQ_NONE;
+
+ spin_lock(&as->lock);
+
+ xfer = as->current_transfer;
+ msg = list_entry(as->queue.next, struct spi_message, queue);
+
+ imr = spi_readl(as, IMR);
+ status = spi_readl(as, SR);
+ pending = status & imr;
+
+ if (pending & SPI_BIT(OVRES)) {
+ int timeout;
+
+ ret = IRQ_HANDLED;
+
+ spi_writel(as, IDR, (SPI_BIT(ENDTX) | SPI_BIT(ENDRX)
+ | SPI_BIT(OVRES)));
+
+ /*
+ * When we get an overrun, we disregard the current
+ * transfer. Data will not be copied back from any
+ * bounce buffer and msg->actual_len will not be
+ * updated with the last xfer.
+ *
+ * We will also not process any remaning transfers in
+ * the message.
+ *
+ * First, stop the transfer and unmap the DMA buffers.
+ */
+ spi_writel(as, PTCR, SPI_BIT(RXTDIS) | SPI_BIT(TXTDIS));
+ if (!msg->is_dma_mapped)
+ atmel_spi_dma_unmap_xfer(master, xfer);
+
+ /* REVISIT: udelay in irq is unfriendly */
+ if (xfer->delay_usecs)
+ udelay(xfer->delay_usecs);
+
+ dev_warn(master->cdev.dev, "fifo overrun (%u/%u remaining)\n",
+ spi_readl(as, TCR), spi_readl(as, RCR));
+
+ /*
+ * Clean up DMA registers and make sure the data
+ * registers are empty.
+ */
+ spi_writel(as, RNCR, 0);
+ spi_writel(as, TNCR, 0);
+ spi_writel(as, RCR, 0);
+ spi_writel(as, TCR, 0);
+ for (timeout = 1000; timeout; timeout--)
+ if (spi_readl(as, SR) & SPI_BIT(TXEMPTY))
+ break;
+ if (!timeout)
+ dev_warn(master->cdev.dev,
+ "timeout waiting for TXEMPTY");
+ while (spi_readl(as, SR) & SPI_BIT(RDRF))
+ spi_readl(as, RDR);
+
+ /* Clear any overrun happening while cleaning up */
+ spi_readl(as, SR);
+
+ atmel_spi_msg_done(master, as, msg, -EIO);
+ } else if (pending & SPI_BIT(ENDRX)) {
+ ret = IRQ_HANDLED;
+
+ spi_writel(as, IDR, pending);
+
+ if (as->remaining_bytes == 0) {
+ msg->actual_length += xfer->len;
+
+ if (!msg->is_dma_mapped)
+ atmel_spi_dma_unmap_xfer(master, xfer);
+
+ /* REVISIT: udelay in irq is unfriendly */
+ if (xfer->delay_usecs)
+ udelay(xfer->delay_usecs);
+
+ if (msg->transfers.prev == &xfer->transfer_list) {
+ /* report completed message */
+ atmel_spi_msg_done(master, as, msg, 0);
+ } else {
+ if (xfer->cs_change) {
+ cs_deactivate(msg->spi);
+ udelay(1);
+ cs_activate(msg->spi);
+ }
+
+ /*
+ * Not done yet. Submit the next transfer.
+ *
+ * FIXME handle protocol options for xfer
+ */
+ atmel_spi_next_xfer(master, msg);
+ }
+ } else {
+ /*
+ * Keep going, we still have data to send in
+ * the current transfer.
+ */
+ atmel_spi_next_xfer(master, msg);
+ }
+ }
+
+ spin_unlock(&as->lock);
+
+ return ret;
+}
+
+#define MODEBITS (SPI_CPOL | SPI_CPHA | SPI_CS_HIGH)
+
+static int atmel_spi_setup(struct spi_device *spi)
+{
+ struct atmel_spi *as;
+ u32 scbr, csr;
+ unsigned int bits = spi->bits_per_word;
+ unsigned long bus_hz, sck_hz;
+ unsigned int npcs_pin;
+ int ret;
+
+ as = spi_master_get_devdata(spi->master);
+
+ if (as->stopping)
+ return -ESHUTDOWN;
+
+ if (spi->chip_select > spi->master->num_chipselect) {
+ dev_dbg(&spi->dev,
+ "setup: invalid chipselect %u (%u defined)\n",
+ spi->chip_select, spi->master->num_chipselect);
+ return -EINVAL;
+ }
+
+ if (bits == 0)
+ bits = 8;
+ if (bits < 8 || bits > 16) {
+ dev_dbg(&spi->dev,
+ "setup: invalid bits_per_word %u (8 to 16)\n",
+ bits);
+ return -EINVAL;
+ }
+
+ if (spi->mode & ~MODEBITS) {
+ dev_dbg(&spi->dev, "setup: unsupported mode bits %x\n",
+ spi->mode & ~MODEBITS);
+ return -EINVAL;
+ }
+
+ /* speed zero convention is used by some upper layers */
+ bus_hz = clk_get_rate(as->clk);
+ if (spi->max_speed_hz) {
+ /* assume div32/fdiv/mbz == 0 */
+ if (!as->new_1)
+ bus_hz /= 2;
+ scbr = ((bus_hz + spi->max_speed_hz - 1)
+ / spi->max_speed_hz);
+ if (scbr >= (1 << SPI_SCBR_SIZE)) {
+ dev_dbg(&spi->dev, "setup: %d Hz too slow, scbr %u\n",
+ spi->max_speed_hz, scbr);
+ return -EINVAL;
+ }
+ } else
+ scbr = 0xff;
+ sck_hz = bus_hz / scbr;
+
+ csr = SPI_BF(SCBR, scbr) | SPI_BF(BITS, bits - 8);
+ if (spi->mode & SPI_CPOL)
+ csr |= SPI_BIT(CPOL);
+ if (!(spi->mode & SPI_CPHA))
+ csr |= SPI_BIT(NCPHA);
+
+ /* TODO: DLYBS and DLYBCT */
+ csr |= SPI_BF(DLYBS, 10);
+ csr |= SPI_BF(DLYBCT, 10);
+
+ /* chipselect must have been muxed as GPIO (e.g. in board setup) */
+ npcs_pin = (unsigned int)spi->controller_data;
+ if (!spi->controller_state) {
+ ret = gpio_request(npcs_pin, "spi_npcs");
+ if (ret)
+ return ret;
+ spi->controller_state = (void *)npcs_pin;
+ gpio_direction_output(npcs_pin);
+ }
+
+ dev_dbg(&spi->dev,
+ "setup: %lu Hz bpw %u mode 0x%x -> csr%d %08x\n",
+ sck_hz, bits, spi->mode, spi->chip_select, csr);
+
+ spi_writel(as, CSR0 + 4 * spi->chip_select, csr);
+
+ return 0;
+}
+
+static int atmel_spi_transfer(struct spi_device *spi, struct spi_message *msg)
+{
+ struct atmel_spi *as;
+ struct spi_transfer *xfer;
+ unsigned long flags;
+ struct device *controller = spi->master->cdev.dev;
+
+ as = spi_master_get_devdata(spi->master);
+
+ dev_dbg(controller, "new message %p submitted for %s\n",
+ msg, spi->dev.bus_id);
+
+ if (unlikely(list_empty(&msg->transfers)
+ || !spi->max_speed_hz))
+ return -EINVAL;
+
+ if (as->stopping)
+ return -ESHUTDOWN;
+
+ list_for_each_entry(xfer, &msg->transfers, transfer_list) {
+ if (!(xfer->tx_buf || xfer->rx_buf)) {
+ dev_dbg(&spi->dev, "missing rx or tx buf\n");
+ return -EINVAL;
+ }
+
+ /* FIXME implement these protocol options!! */
+ if (xfer->bits_per_word || xfer->speed_hz) {
+ dev_dbg(&spi->dev, "no protocol options yet\n");
+ return -ENOPROTOOPT;
+ }
+ }
+
+ /* scrub dcache "early" */
+ if (!msg->is_dma_mapped) {
+ list_for_each_entry(xfer, &msg->transfers, transfer_list)
+ atmel_spi_dma_map_xfer(as, xfer);
+ }
+
+ list_for_each_entry(xfer, &msg->transfers, transfer_list) {
+ dev_dbg(controller,
+ " xfer %p: len %u tx %p/%08x rx %p/%08x\n",
+ xfer, xfer->len,
+ xfer->tx_buf, xfer->tx_dma,
+ xfer->rx_buf, xfer->rx_dma);
+ }
+
+ msg->status = -EINPROGRESS;
+ msg->actual_length = 0;
+
+ spin_lock_irqsave(&as->lock, flags);
+ list_add_tail(&msg->queue, &as->queue);
+ if (!as->current_transfer)
+ atmel_spi_next_message(spi->master);
+ spin_unlock_irqrestore(&as->lock, flags);
+
+ return 0;
+}
+
+static void atmel_spi_cleanup(const struct spi_device *spi)
+{
+ if (spi->controller_state)
+ gpio_free((unsigned int)spi->controller_data);
+}
+
+/*-------------------------------------------------------------------------*/
+
+static int __init atmel_spi_probe(struct platform_device *pdev)
+{
+ struct resource *regs;
+ int irq;
+ struct clk *clk;
+ int ret;
+ struct spi_master *master;
+ struct atmel_spi *as;
+
+ regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ if (!regs)
+ return -ENXIO;
+
+ irq = platform_get_irq(pdev, 0);
+ if (irq < 0)
+ return irq;
+
+ clk = clk_get(&pdev->dev, "spi_clk");
+ if (IS_ERR(clk))
+ return PTR_ERR(clk);
+
+ /* setup spi core then atmel-specific driver state */
+ ret = -ENOMEM;
+ master = spi_alloc_master(&pdev->dev, sizeof *as);
+ if (!master)
+ goto out_free;
+
+ master->bus_num = pdev->id;
+ master->num_chipselect = 4;
+ master->setup = atmel_spi_setup;
+ master->transfer = atmel_spi_transfer;
+ master->cleanup = atmel_spi_cleanup;
+ platform_set_drvdata(pdev, master);
+
+ as = spi_master_get_devdata(master);
+
+ as->buffer = dma_alloc_coherent(&pdev->dev, BUFFER_SIZE,
+ &as->buffer_dma, GFP_KERNEL);
+ if (!as->buffer)
+ goto out_free;
+
+ spin_lock_init(&as->lock);
+ INIT_LIST_HEAD(&as->queue);
+ as->pdev = pdev;
+ as->regs = ioremap(regs->start, (regs->end - regs->start) + 1);
+ if (!as->regs)
+ goto out_free_buffer;
+ as->irq = irq;
+ as->clk = clk;
+#ifdef CONFIG_ARCH_AT91
+ if (!cpu_is_at91rm9200())
+ as->new_1 = 1;
+#endif
+
+ ret = request_irq(irq, atmel_spi_interrupt, 0,
+ pdev->dev.bus_id, master);
+ if (ret)
+ goto out_unmap_regs;
+
+ /* Initialize the hardware */
+ clk_enable(clk);
+ spi_writel(as, CR, SPI_BIT(SWRST));
+ spi_writel(as, MR, SPI_BIT(MSTR) | SPI_BIT(MODFDIS));
+ spi_writel(as, PTCR, SPI_BIT(RXTDIS) | SPI_BIT(TXTDIS));
+ spi_writel(as, CR, SPI_BIT(SPIEN));
+
+ /* go! */
+ dev_info(&pdev->dev, "Atmel SPI Controller at 0x%08lx (irq %d)\n",
+ (unsigned long)regs->start, irq);
+
+ ret = spi_register_master(master);
+ if (ret)
+ goto out_reset_hw;
+
+ return 0;
+
+out_reset_hw:
+ spi_writel(as, CR, SPI_BIT(SWRST));
+ clk_disable(clk);
+ free_irq(irq, master);
+out_unmap_regs:
+ iounmap(as->regs);
+out_free_buffer:
+ dma_free_coherent(&pdev->dev, BUFFER_SIZE, as->buffer,
+ as->buffer_dma);
+out_free:
+ clk_put(clk);
+ spi_master_put(master);
+ return ret;
+}
+
+static int __exit atmel_spi_remove(struct platform_device *pdev)
+{
+ struct spi_master *master = platform_get_drvdata(pdev);
+ struct atmel_spi *as = spi_master_get_devdata(master);
+ struct spi_message *msg;
+
+ /* reset the hardware and block queue progress */
+ spin_lock_irq(&as->lock);
+ as->stopping = 1;
+ spi_writel(as, CR, SPI_BIT(SWRST));
+ spi_readl(as, SR);
+ spin_unlock_irq(&as->lock);
+
+ /* Terminate remaining queued transfers */
+ list_for_each_entry(msg, &as->queue, queue) {
+ /* REVISIT unmapping the dma is a NOP on ARM and AVR32
+ * but we shouldn't depend on that...
+ */
+ msg->status = -ESHUTDOWN;
+ msg->complete(msg->context);
+ }
+
+ dma_free_coherent(&pdev->dev, BUFFER_SIZE, as->buffer,
+ as->buffer_dma);
+
+ clk_disable(as->clk);
+ clk_put(as->clk);
+ free_irq(as->irq, master);
+ iounmap(as->regs);
+
+ spi_unregister_master(master);
+
+ return 0;
+}
+
+#ifdef CONFIG_PM
+
+static int atmel_spi_suspend(struct platform_device *pdev, pm_message_t mesg)
+{
+ struct spi_master *master = platform_get_drvdata(pdev);
+ struct atmel_spi *as = spi_master_get_devdata(master);
+
+ clk_disable(as->clk);
+ return 0;
+}
+
+static int atmel_spi_resume(struct platform_device *pdev)
+{
+ struct spi_master *master = platform_get_drvdata(pdev);
+ struct atmel_spi *as = spi_master_get_devdata(master);
+
+ clk_enable(as->clk);
+ return 0;
+}
+
+#else
+#define atmel_spi_suspend NULL
+#define atmel_spi_resume NULL
+#endif
+
+
+static struct platform_driver atmel_spi_driver = {
+ .driver = {
+ .name = "atmel_spi",
+ .owner = THIS_MODULE,
+ },
+ .suspend = atmel_spi_suspend,
+ .resume = atmel_spi_resume,
+ .remove = __exit_p(atmel_spi_remove),
+};
+
+static int __init atmel_spi_init(void)
+{
+ return platform_driver_probe(&atmel_spi_driver, atmel_spi_probe);
+}
+module_init(atmel_spi_init);
+
+static void __exit atmel_spi_exit(void)
+{
+ platform_driver_unregister(&atmel_spi_driver);
+}
+module_exit(atmel_spi_exit);
+
+MODULE_DESCRIPTION("Atmel AT32/AT91 SPI Controller driver");
+MODULE_AUTHOR("Haavard Skinnemoen <hskinnemoen@atmel.com>");
+MODULE_LICENSE("GPL");