/*
* 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;
struct spi_device *stay;
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. ("NPCSx rises if no data is to be
* transmitted") 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, updating
* MR.PCS to avoid confusing the controller. Using GPIOs also lets us
* support active-high chipselects despite the controller's belief that
* only active-low devices/systems exists.
*
* However, at91rm9200 has a second erratum whereby nCS0 doesn't work
* right when driven with GPIO. ("Mode Fault does not allow more than one
* Master on Chip Select 0.") No workaround exists for that ... so for
* nCS0 on that chip, we (a) don't use the GPIO, (b) can't support CS_HIGH,
* and (c) will trigger that first erratum in some cases.
*/
static void cs_activate(struct atmel_spi *as, struct spi_device *spi)
{
unsigned gpio = (unsigned) spi->controller_data;
unsigned active = spi->mode & SPI_CS_HIGH;
u32 mr;
mr = spi_readl(as, MR);
mr = SPI_BFINS(PCS, ~(1 << spi->chip_select), mr);
dev_dbg(&spi->dev, "activate %u%s, mr %08x\n",
gpio, active ? " (high)" : "",
mr);
if (!(cpu_is_at91rm9200() && spi->chip_select == 0))
gpio_set_value(gpio, active);
spi_writel(as, MR, mr);
}
static void cs_deactivate(struct atmel_spi *as, struct spi_device *spi)
{
unsigned gpio = (unsigned) spi->controller_data;
unsigned active = spi->mode & SPI_CS_HIGH;
u32 mr;
/* only deactivate *this* device; sometimes transfers to
* another device may be active when this routine is called.
*/
mr = spi_readl(as, MR);
if (~SPI_BFEXT(PCS, mr) & (1 << spi->chip_select)) {
mr = SPI_BFINS(PCS, 0xf, mr);
spi_writel(as, MR, mr);
}
dev_dbg(&spi->dev, "DEactivate %u%s, mr %08x\n",
gpio, active ? " (low)" : "",
mr);
if (!(cpu_is_at91rm9200() && spi->chip_select == 0))
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
* (and improve the nCS0 errata handling on at91rm9200 chips)
*
* 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;
struct spi_device *spi;
BUG_ON(as->current_transfer);
msg = list_entry(as->queue.next, struct spi_message, queue);
spi = msg->spi;
dev_dbg(master->cdev.dev, "start message %p for %s\n",
msg, spi->dev.bus_id);
/* select chip if it's not still active */
if (as->stay) {
if (as->stay != spi) {
cs_deactivate(as, as->stay);
cs_activate(as, spi);
}
as->stay = NULL;
} else
cs_activate(as, 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->rx_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, int stay)
{
if (!stay || status < 0)
cs_deactivate(as, msg->spi);
else
as->stay = 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, 0);
} 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,
xfer->cs_change);
} else {
if (xfer->cs_change) {
cs_deactivate(as, msg->spi);
udelay(1);
cs_activate(as, 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;
}
/* see notes above re chipselect */
if (cpu_is_at91rm9200()
&& spi->chip_select == 0
&& (spi->mode & SPI_CS_HIGH)) {
dev_dbg(&spi->dev, "setup: can't be active-high\n");
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));
} else {
unsigned long flags;
spin_lock_irqsave(&as->lock, flags);
if (as->stay == spi)
as->stay = NULL;
cs_deactivate(as, spi);
spin_unlock_irqrestore(&as->lock, flags);
}
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;
}
}
#ifdef VERBOSE
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);
}
#endif
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)
{
struct atmel_spi *as = spi_master_get_devdata(spi->master);
unsigned gpio = (unsigned) spi->controller_data;
unsigned long flags;
if (!spi->controller_state)
return;
spin_lock_irqsave(&as->lock, flags);
if (as->stay == spi) {
as->stay = NULL;
cs_deactivate(as, spi);
}
spin_unlock_irqrestore(&as->lock, flags);
gpio_free(gpio);
}
/*-------------------------------------------------------------------------*/
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");
