diff options
Diffstat (limited to 'drivers/spi/atmel_spi.c')
| -rw-r--r-- | drivers/spi/atmel_spi.c | 678 |
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"); |