linux/drivers/spi/spi_s3c24xx.c

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/* linux/drivers/spi/spi_s3c24xx.c
*
* Copyright (c) 2006 Ben Dooks
* Copyright (c) 2006 Simtec Electronics
* Ben Dooks <ben@simtec.co.uk>
*
* 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/spinlock.h>
#include <linux/workqueue.h>
#include <linux/interrupt.h>
#include <linux/delay.h>
#include <linux/errno.h>
#include <linux/err.h>
#include <linux/clk.h>
#include <linux/platform_device.h>
#include <linux/spi/spi.h>
#include <linux/spi/spi_bitbang.h>
#include <asm/io.h>
#include <asm/dma.h>
#include <asm/hardware.h>
#include <asm/arch/regs-gpio.h>
#include <asm/plat-s3c24xx/regs-spi.h>
#include <asm/arch/spi.h>
struct s3c24xx_spi {
/* bitbang has to be first */
struct spi_bitbang bitbang;
struct completion done;
void __iomem *regs;
int irq;
int len;
int count;
void (*set_cs)(struct s3c2410_spi_info *spi,
int cs, int pol);
/* data buffers */
const unsigned char *tx;
unsigned char *rx;
struct clk *clk;
struct resource *ioarea;
struct spi_master *master;
struct spi_device *curdev;
struct device *dev;
struct s3c2410_spi_info *pdata;
};
#define SPCON_DEFAULT (S3C2410_SPCON_MSTR | S3C2410_SPCON_SMOD_INT)
#define SPPIN_DEFAULT (S3C2410_SPPIN_KEEP)
static inline struct s3c24xx_spi *to_hw(struct spi_device *sdev)
{
return spi_master_get_devdata(sdev->master);
}
static void s3c24xx_spi_gpiocs(struct s3c2410_spi_info *spi, int cs, int pol)
{
s3c2410_gpio_setpin(spi->pin_cs, pol);
}
static void s3c24xx_spi_chipsel(struct spi_device *spi, int value)
{
struct s3c24xx_spi *hw = to_hw(spi);
unsigned int cspol = spi->mode & SPI_CS_HIGH ? 1 : 0;
unsigned int spcon;
switch (value) {
case BITBANG_CS_INACTIVE:
hw->set_cs(hw->pdata, spi->chip_select, cspol^1);
break;
case BITBANG_CS_ACTIVE:
spcon = readb(hw->regs + S3C2410_SPCON);
if (spi->mode & SPI_CPHA)
spcon |= S3C2410_SPCON_CPHA_FMTB;
else
spcon &= ~S3C2410_SPCON_CPHA_FMTB;
if (spi->mode & SPI_CPOL)
spcon |= S3C2410_SPCON_CPOL_HIGH;
else
spcon &= ~S3C2410_SPCON_CPOL_HIGH;
spcon |= S3C2410_SPCON_ENSCK;
/* write new configration */
writeb(spcon, hw->regs + S3C2410_SPCON);
hw->set_cs(hw->pdata, spi->chip_select, cspol);
break;
}
}
static int s3c24xx_spi_setupxfer(struct spi_device *spi,
struct spi_transfer *t)
{
struct s3c24xx_spi *hw = to_hw(spi);
unsigned int bpw;
unsigned int hz;
unsigned int div;
bpw = t ? t->bits_per_word : spi->bits_per_word;
hz = t ? t->speed_hz : spi->max_speed_hz;
if (bpw != 8) {
dev_err(&spi->dev, "invalid bits-per-word (%d)\n", bpw);
return -EINVAL;
}
div = clk_get_rate(hw->clk) / hz;
/* is clk = pclk / (2 * (pre+1)), or is it
* clk = (pclk * 2) / ( pre + 1) */
div = (div / 2) - 1;
if (div < 0)
div = 1;
if (div > 255)
div = 255;
dev_dbg(&spi->dev, "setting pre-scaler to %d (hz %d)\n", div, hz);
writeb(div, hw->regs + S3C2410_SPPRE);
spin_lock(&hw->bitbang.lock);
if (!hw->bitbang.busy) {
hw->bitbang.chipselect(spi, BITBANG_CS_INACTIVE);
/* need to ndelay for 0.5 clocktick ? */
}
spin_unlock(&hw->bitbang.lock);
return 0;
}
/* the spi->mode bits understood by this driver: */
#define MODEBITS (SPI_CPOL | SPI_CPHA | SPI_CS_HIGH)
static int s3c24xx_spi_setup(struct spi_device *spi)
{
int ret;
if (!spi->bits_per_word)
spi->bits_per_word = 8;
if (spi->mode & ~MODEBITS) {
dev_dbg(&spi->dev, "setup: unsupported mode bits %x\n",
spi->mode & ~MODEBITS);
return -EINVAL;
}
ret = s3c24xx_spi_setupxfer(spi, NULL);
if (ret < 0) {
dev_err(&spi->dev, "setupxfer returned %d\n", ret);
return ret;
}
dev_dbg(&spi->dev, "%s: mode %d, %u bpw, %d hz\n",
__FUNCTION__, spi->mode, spi->bits_per_word,
spi->max_speed_hz);
return 0;
}
static inline unsigned int hw_txbyte(struct s3c24xx_spi *hw, int count)
{
return hw->tx ? hw->tx[count] : 0;
}
static int s3c24xx_spi_txrx(struct spi_device *spi, struct spi_transfer *t)
{
struct s3c24xx_spi *hw = to_hw(spi);
dev_dbg(&spi->dev, "txrx: tx %p, rx %p, len %d\n",
t->tx_buf, t->rx_buf, t->len);
hw->tx = t->tx_buf;
hw->rx = t->rx_buf;
hw->len = t->len;
hw->count = 0;
/* send the first byte */
writeb(hw_txbyte(hw, 0), hw->regs + S3C2410_SPTDAT);
wait_for_completion(&hw->done);
return hw->count;
}
IRQ: Maintain regs pointer globally rather than passing to IRQ handlers Maintain a per-CPU global "struct pt_regs *" variable which can be used instead of passing regs around manually through all ~1800 interrupt handlers in the Linux kernel. The regs pointer is used in few places, but it potentially costs both stack space and code to pass it around. On the FRV arch, removing the regs parameter from all the genirq function results in a 20% speed up of the IRQ exit path (ie: from leaving timer_interrupt() to leaving do_IRQ()). Where appropriate, an arch may override the generic storage facility and do something different with the variable. On FRV, for instance, the address is maintained in GR28 at all times inside the kernel as part of general exception handling. Having looked over the code, it appears that the parameter may be handed down through up to twenty or so layers of functions. Consider a USB character device attached to a USB hub, attached to a USB controller that posts its interrupts through a cascaded auxiliary interrupt controller. A character device driver may want to pass regs to the sysrq handler through the input layer which adds another few layers of parameter passing. I've build this code with allyesconfig for x86_64 and i386. I've runtested the main part of the code on FRV and i386, though I can't test most of the drivers. I've also done partial conversion for powerpc and MIPS - these at least compile with minimal configurations. This will affect all archs. Mostly the changes should be relatively easy. Take do_IRQ(), store the regs pointer at the beginning, saving the old one: struct pt_regs *old_regs = set_irq_regs(regs); And put the old one back at the end: set_irq_regs(old_regs); Don't pass regs through to generic_handle_irq() or __do_IRQ(). In timer_interrupt(), this sort of change will be necessary: - update_process_times(user_mode(regs)); - profile_tick(CPU_PROFILING, regs); + update_process_times(user_mode(get_irq_regs())); + profile_tick(CPU_PROFILING); I'd like to move update_process_times()'s use of get_irq_regs() into itself, except that i386, alone of the archs, uses something other than user_mode(). Some notes on the interrupt handling in the drivers: (*) input_dev() is now gone entirely. The regs pointer is no longer stored in the input_dev struct. (*) finish_unlinks() in drivers/usb/host/ohci-q.c needs checking. It does something different depending on whether it's been supplied with a regs pointer or not. (*) Various IRQ handler function pointers have been moved to type irq_handler_t. Signed-Off-By: David Howells <dhowells@redhat.com> (cherry picked from 1b16e7ac850969f38b375e511e3fa2f474a33867 commit)
2006-10-05 13:55:46 +00:00
static irqreturn_t s3c24xx_spi_irq(int irq, void *dev)
{
struct s3c24xx_spi *hw = dev;
unsigned int spsta = readb(hw->regs + S3C2410_SPSTA);
unsigned int count = hw->count;
if (spsta & S3C2410_SPSTA_DCOL) {
dev_dbg(hw->dev, "data-collision\n");
complete(&hw->done);
goto irq_done;
}
if (!(spsta & S3C2410_SPSTA_READY)) {
dev_dbg(hw->dev, "spi not ready for tx?\n");
complete(&hw->done);
goto irq_done;
}
hw->count++;
if (hw->rx)
hw->rx[count] = readb(hw->regs + S3C2410_SPRDAT);
count++;
if (count < hw->len)
writeb(hw_txbyte(hw, count), hw->regs + S3C2410_SPTDAT);
else
complete(&hw->done);
irq_done:
return IRQ_HANDLED;
}
static int __init s3c24xx_spi_probe(struct platform_device *pdev)
{
struct s3c24xx_spi *hw;
struct spi_master *master;
struct spi_board_info *bi;
struct resource *res;
int err = 0;
int i;
master = spi_alloc_master(&pdev->dev, sizeof(struct s3c24xx_spi));
if (master == NULL) {
dev_err(&pdev->dev, "No memory for spi_master\n");
err = -ENOMEM;
goto err_nomem;
}
hw = spi_master_get_devdata(master);
memset(hw, 0, sizeof(struct s3c24xx_spi));
hw->master = spi_master_get(master);
hw->pdata = pdev->dev.platform_data;
hw->dev = &pdev->dev;
if (hw->pdata == NULL) {
dev_err(&pdev->dev, "No platform data supplied\n");
err = -ENOENT;
goto err_no_pdata;
}
platform_set_drvdata(pdev, hw);
init_completion(&hw->done);
/* setup the state for the bitbang driver */
hw->bitbang.master = hw->master;
hw->bitbang.setup_transfer = s3c24xx_spi_setupxfer;
hw->bitbang.chipselect = s3c24xx_spi_chipsel;
hw->bitbang.txrx_bufs = s3c24xx_spi_txrx;
hw->bitbang.master->setup = s3c24xx_spi_setup;
dev_dbg(hw->dev, "bitbang at %p\n", &hw->bitbang);
/* find and map our resources */
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (res == NULL) {
dev_err(&pdev->dev, "Cannot get IORESOURCE_MEM\n");
err = -ENOENT;
goto err_no_iores;
}
hw->ioarea = request_mem_region(res->start, (res->end - res->start)+1,
pdev->name);
if (hw->ioarea == NULL) {
dev_err(&pdev->dev, "Cannot reserve region\n");
err = -ENXIO;
goto err_no_iores;
}
hw->regs = ioremap(res->start, (res->end - res->start)+1);
if (hw->regs == NULL) {
dev_err(&pdev->dev, "Cannot map IO\n");
err = -ENXIO;
goto err_no_iomap;
}
hw->irq = platform_get_irq(pdev, 0);
if (hw->irq < 0) {
dev_err(&pdev->dev, "No IRQ specified\n");
err = -ENOENT;
goto err_no_irq;
}
err = request_irq(hw->irq, s3c24xx_spi_irq, 0, pdev->name, hw);
if (err) {
dev_err(&pdev->dev, "Cannot claim IRQ\n");
goto err_no_irq;
}
hw->clk = clk_get(&pdev->dev, "spi");
if (IS_ERR(hw->clk)) {
dev_err(&pdev->dev, "No clock for device\n");
err = PTR_ERR(hw->clk);
goto err_no_clk;
}
/* for the moment, permanently enable the clock */
clk_enable(hw->clk);
/* program defaults into the registers */
writeb(0xff, hw->regs + S3C2410_SPPRE);
writeb(SPPIN_DEFAULT, hw->regs + S3C2410_SPPIN);
writeb(SPCON_DEFAULT, hw->regs + S3C2410_SPCON);
/* setup any gpio we can */
if (!hw->pdata->set_cs) {
hw->set_cs = s3c24xx_spi_gpiocs;
s3c2410_gpio_setpin(hw->pdata->pin_cs, 1);
s3c2410_gpio_cfgpin(hw->pdata->pin_cs, S3C2410_GPIO_OUTPUT);
} else
hw->set_cs = hw->pdata->set_cs;
/* register our spi controller */
err = spi_bitbang_start(&hw->bitbang);
if (err) {
dev_err(&pdev->dev, "Failed to register SPI master\n");
goto err_register;
}
/* register all the devices associated */
bi = &hw->pdata->board_info[0];
for (i = 0; i < hw->pdata->board_size; i++, bi++) {
dev_info(hw->dev, "registering %s\n", bi->modalias);
bi->controller_data = hw;
spi_new_device(master, bi);
}
return 0;
err_register:
clk_disable(hw->clk);
clk_put(hw->clk);
err_no_clk:
free_irq(hw->irq, hw);
err_no_irq:
iounmap(hw->regs);
err_no_iomap:
release_resource(hw->ioarea);
kfree(hw->ioarea);
err_no_iores:
err_no_pdata:
spi_master_put(hw->master);;
err_nomem:
return err;
}
static int __exit s3c24xx_spi_remove(struct platform_device *dev)
{
struct s3c24xx_spi *hw = platform_get_drvdata(dev);
platform_set_drvdata(dev, NULL);
spi_unregister_master(hw->master);
clk_disable(hw->clk);
clk_put(hw->clk);
free_irq(hw->irq, hw);
iounmap(hw->regs);
release_resource(hw->ioarea);
kfree(hw->ioarea);
spi_master_put(hw->master);
return 0;
}
#ifdef CONFIG_PM
static int s3c24xx_spi_suspend(struct platform_device *pdev, pm_message_t msg)
{
struct s3c24xx_spi *hw = platform_get_drvdata(pdev);
clk_disable(hw->clk);
return 0;
}
static int s3c24xx_spi_resume(struct platform_device *pdev)
{
struct s3c24xx_spi *hw = platform_get_drvdata(pdev);
clk_enable(hw->clk);
return 0;
}
#else
#define s3c24xx_spi_suspend NULL
#define s3c24xx_spi_resume NULL
#endif
MODULE_ALIAS("s3c2410_spi"); /* for platform bus hotplug */
static struct platform_driver s3c24xx_spidrv = {
.remove = __exit_p(s3c24xx_spi_remove),
.suspend = s3c24xx_spi_suspend,
.resume = s3c24xx_spi_resume,
.driver = {
.name = "s3c2410-spi",
.owner = THIS_MODULE,
},
};
static int __init s3c24xx_spi_init(void)
{
return platform_driver_probe(&s3c24xx_spidrv, s3c24xx_spi_probe);
}
static void __exit s3c24xx_spi_exit(void)
{
platform_driver_unregister(&s3c24xx_spidrv);
}
module_init(s3c24xx_spi_init);
module_exit(s3c24xx_spi_exit);
MODULE_DESCRIPTION("S3C24XX SPI Driver");
MODULE_AUTHOR("Ben Dooks, <ben@simtec.co.uk>");
MODULE_LICENSE("GPL");