/* * 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 <asm/arch/cpu.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 + xfer->len - len; rx_dma = xfer->rx_dma + xfer->len - len; /* use scratch buffer only when rx or tx data is unspecified */ if (!xfer->rx_buf) { rx_dma = as->buffer_dma; if (len > BUFFER_SIZE) len = BUFFER_SIZE; } if (!xfer->tx_buf) { 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); } /* * For DMA, tx_buf/tx_dma have the same relationship as rx_buf/rx_dma: * - The buffer is either valid for CPU access, else NULL * - If the buffer is valid, so is its DMA addresss * * This driver manages the dma addresss unless message->is_dma_mapped. */ static int atmel_spi_dma_map_xfer(struct atmel_spi *as, struct spi_transfer *xfer) { struct device *dev = &as->pdev->dev; xfer->tx_dma = xfer->rx_dma = INVALID_DMA_ADDRESS; if (xfer->tx_buf) { xfer->tx_dma = dma_map_single(dev, (void *) xfer->tx_buf, xfer->len, DMA_TO_DEVICE); if (dma_mapping_error(xfer->tx_dma)) return -ENOMEM; } if (xfer->rx_buf) { xfer->rx_dma = dma_map_single(dev, xfer->rx_buf, xfer->len, DMA_FROM_DEVICE); if (dma_mapping_error(xfer->tx_dma)) { if (xfer->tx_buf) dma_unmap_single(dev, xfer->tx_dma, xfer->len, DMA_TO_DEVICE); return -ENOMEM; } } return 0; } 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; } /* the spi->mode bits understood by this driver: */ #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; min %ld Hz\n", spi->max_speed_hz, scbr, bus_hz/255); 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, !(spi->mode & SPI_CS_HIGH)); } 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; } /* * DMA map early, for performance (empties dcache ASAP) and * better fault reporting. This is a DMA-only driver. * * NOTE that if dma_unmap_single() ever starts to do work on * platforms supported by this driver, we would need to clean * up mappings for previously-mapped transfers. */ if (!msg->is_dma_mapped) { if (atmel_spi_dma_map_xfer(as, xfer) < 0) return -ENOMEM; } } 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(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); /* * Scratch buffer is used for throwaway rx and tx data. * It's coherent to minimize dcache pollution. */ 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; if (!cpu_is_at91rm9200()) as->new_1 = 1; 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");