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linux/drivers/spi/spi-txx9.c
Bhaktipriya Shridhar b43afff7dc spi: spi-txx9: Remove deprecated create_singlethread_workqueue 
The workqueue "workqueue" has a single work item(&c->work) and hence
doesn't require ordering. Also, it is not being used on a memory reclaim
path. Hence, the singlethreaded workqueue has been replaced with the use of
system_wq.

System workqueues have been able to handle high level of concurrency
for a long time now and hence it's not required to have a singlethreaded
workqueue just to gain concurrency. Unlike a dedicated per-cpu workqueue
created with create_singlethread_workqueue(), system_wq allows multiple
work items to overlap executions even on the same CPU; however, a
per-cpu workqueue doesn't have any CPU locality or global ordering
guarantee unless the target CPU is explicitly specified and thus the
increase of local concurrency shouldn't make any difference.

Work item has been flushed in txx9spi_remove() to ensure that
nothing is pending while disconnecting the driver.

Signed-off-by: Bhaktipriya Shridhar <bhaktipriya96@gmail.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
2016-07-03 14:22:27 +02:00

438 lines
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/*
* TXx9 SPI controller driver.
*
* Based on linux/arch/mips/tx4938/toshiba_rbtx4938/spi_txx9.c
* Copyright (C) 2000-2001 Toshiba Corporation
*
* 2003-2005 (c) MontaVista Software, Inc. This file is licensed under the
* terms of the GNU General Public License version 2. This program is
* licensed "as is" without any warranty of any kind, whether express
* or implied.
*
* Support for TX4938 in 2.6 - Manish Lachwani (mlachwani@mvista.com)
*
* Convert to generic SPI framework - Atsushi Nemoto (anemo@mba.ocn.ne.jp)
*/
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/errno.h>
#include <linux/interrupt.h>
#include <linux/platform_device.h>
#include <linux/sched.h>
#include <linux/spinlock.h>
#include <linux/workqueue.h>
#include <linux/spi/spi.h>
#include <linux/err.h>
#include <linux/clk.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/gpio.h>
#define SPI_FIFO_SIZE 4
#define SPI_MAX_DIVIDER 0xff /* Max. value for SPCR1.SER */
#define SPI_MIN_DIVIDER 1 /* Min. value for SPCR1.SER */
#define TXx9_SPMCR 0x00
#define TXx9_SPCR0 0x04
#define TXx9_SPCR1 0x08
#define TXx9_SPFS 0x0c
#define TXx9_SPSR 0x14
#define TXx9_SPDR 0x18
/* SPMCR : SPI Master Control */
#define TXx9_SPMCR_OPMODE 0xc0
#define TXx9_SPMCR_CONFIG 0x40
#define TXx9_SPMCR_ACTIVE 0x80
#define TXx9_SPMCR_SPSTP 0x02
#define TXx9_SPMCR_BCLR 0x01
/* SPCR0 : SPI Control 0 */
#define TXx9_SPCR0_TXIFL_MASK 0xc000
#define TXx9_SPCR0_RXIFL_MASK 0x3000
#define TXx9_SPCR0_SIDIE 0x0800
#define TXx9_SPCR0_SOEIE 0x0400
#define TXx9_SPCR0_RBSIE 0x0200
#define TXx9_SPCR0_TBSIE 0x0100
#define TXx9_SPCR0_IFSPSE 0x0010
#define TXx9_SPCR0_SBOS 0x0004
#define TXx9_SPCR0_SPHA 0x0002
#define TXx9_SPCR0_SPOL 0x0001
/* SPSR : SPI Status */
#define TXx9_SPSR_TBSI 0x8000
#define TXx9_SPSR_RBSI 0x4000
#define TXx9_SPSR_TBS_MASK 0x3800
#define TXx9_SPSR_RBS_MASK 0x0700
#define TXx9_SPSR_SPOE 0x0080
#define TXx9_SPSR_IFSD 0x0008
#define TXx9_SPSR_SIDLE 0x0004
#define TXx9_SPSR_STRDY 0x0002
#define TXx9_SPSR_SRRDY 0x0001
struct txx9spi {
struct work_struct work;
spinlock_t lock; /* protect 'queue' */
struct list_head queue;
wait_queue_head_t waitq;
void __iomem *membase;
int baseclk;
struct clk *clk;
int last_chipselect;
int last_chipselect_val;
};
static u32 txx9spi_rd(struct txx9spi *c, int reg)
{
return __raw_readl(c->membase + reg);
}
static void txx9spi_wr(struct txx9spi *c, u32 val, int reg)
{
__raw_writel(val, c->membase + reg);
}
static void txx9spi_cs_func(struct spi_device *spi, struct txx9spi *c,
int on, unsigned int cs_delay)
{
int val = (spi->mode & SPI_CS_HIGH) ? on : !on;
if (on) {
/* deselect the chip with cs_change hint in last transfer */
if (c->last_chipselect >= 0)
gpio_set_value(c->last_chipselect,
!c->last_chipselect_val);
c->last_chipselect = spi->chip_select;
c->last_chipselect_val = val;
} else {
c->last_chipselect = -1;
ndelay(cs_delay); /* CS Hold Time */
}
gpio_set_value(spi->chip_select, val);
ndelay(cs_delay); /* CS Setup Time / CS Recovery Time */
}
static int txx9spi_setup(struct spi_device *spi)
{
struct txx9spi *c = spi_master_get_devdata(spi->master);
if (!spi->max_speed_hz)
return -EINVAL;
if (gpio_direction_output(spi->chip_select,
!(spi->mode & SPI_CS_HIGH))) {
dev_err(&spi->dev, "Cannot setup GPIO for chipselect.\n");
return -EINVAL;
}
/* deselect chip */
spin_lock(&c->lock);
txx9spi_cs_func(spi, c, 0, (NSEC_PER_SEC / 2) / spi->max_speed_hz);
spin_unlock(&c->lock);
return 0;
}
static irqreturn_t txx9spi_interrupt(int irq, void *dev_id)
{
struct txx9spi *c = dev_id;
/* disable rx intr */
txx9spi_wr(c, txx9spi_rd(c, TXx9_SPCR0) & ~TXx9_SPCR0_RBSIE,
TXx9_SPCR0);
wake_up(&c->waitq);
return IRQ_HANDLED;
}
static void txx9spi_work_one(struct txx9spi *c, struct spi_message *m)
{
struct spi_device *spi = m->spi;
struct spi_transfer *t;
unsigned int cs_delay;
unsigned int cs_change = 1;
int status = 0;
u32 mcr;
u32 prev_speed_hz = 0;
u8 prev_bits_per_word = 0;
/* CS setup/hold/recovery time in nsec */
cs_delay = 100 + (NSEC_PER_SEC / 2) / spi->max_speed_hz;
mcr = txx9spi_rd(c, TXx9_SPMCR);
if (unlikely((mcr & TXx9_SPMCR_OPMODE) == TXx9_SPMCR_ACTIVE)) {
dev_err(&spi->dev, "Bad mode.\n");
status = -EIO;
goto exit;
}
mcr &= ~(TXx9_SPMCR_OPMODE | TXx9_SPMCR_SPSTP | TXx9_SPMCR_BCLR);
/* enter config mode */
txx9spi_wr(c, mcr | TXx9_SPMCR_CONFIG | TXx9_SPMCR_BCLR, TXx9_SPMCR);
txx9spi_wr(c, TXx9_SPCR0_SBOS
| ((spi->mode & SPI_CPOL) ? TXx9_SPCR0_SPOL : 0)
| ((spi->mode & SPI_CPHA) ? TXx9_SPCR0_SPHA : 0)
| 0x08,
TXx9_SPCR0);
list_for_each_entry(t, &m->transfers, transfer_list) {
const void *txbuf = t->tx_buf;
void *rxbuf = t->rx_buf;
u32 data;
unsigned int len = t->len;
unsigned int wsize;
u32 speed_hz = t->speed_hz;
u8 bits_per_word = t->bits_per_word;
wsize = bits_per_word >> 3; /* in bytes */
if (prev_speed_hz != speed_hz
|| prev_bits_per_word != bits_per_word) {
int n = DIV_ROUND_UP(c->baseclk, speed_hz) - 1;
n = clamp(n, SPI_MIN_DIVIDER, SPI_MAX_DIVIDER);
/* enter config mode */
txx9spi_wr(c, mcr | TXx9_SPMCR_CONFIG | TXx9_SPMCR_BCLR,
TXx9_SPMCR);
txx9spi_wr(c, (n << 8) | bits_per_word, TXx9_SPCR1);
/* enter active mode */
txx9spi_wr(c, mcr | TXx9_SPMCR_ACTIVE, TXx9_SPMCR);
prev_speed_hz = speed_hz;
prev_bits_per_word = bits_per_word;
}
if (cs_change)
txx9spi_cs_func(spi, c, 1, cs_delay);
cs_change = t->cs_change;
while (len) {
unsigned int count = SPI_FIFO_SIZE;
int i;
u32 cr0;
if (len < count * wsize)
count = len / wsize;
/* now tx must be idle... */
while (!(txx9spi_rd(c, TXx9_SPSR) & TXx9_SPSR_SIDLE))
cpu_relax();
cr0 = txx9spi_rd(c, TXx9_SPCR0);
cr0 &= ~TXx9_SPCR0_RXIFL_MASK;
cr0 |= (count - 1) << 12;
/* enable rx intr */
cr0 |= TXx9_SPCR0_RBSIE;
txx9spi_wr(c, cr0, TXx9_SPCR0);
/* send */
for (i = 0; i < count; i++) {
if (txbuf) {
data = (wsize == 1)
? *(const u8 *)txbuf
: *(const u16 *)txbuf;
txx9spi_wr(c, data, TXx9_SPDR);
txbuf += wsize;
} else
txx9spi_wr(c, 0, TXx9_SPDR);
}
/* wait all rx data */
wait_event(c->waitq,
txx9spi_rd(c, TXx9_SPSR) & TXx9_SPSR_RBSI);
/* receive */
for (i = 0; i < count; i++) {
data = txx9spi_rd(c, TXx9_SPDR);
if (rxbuf) {
if (wsize == 1)
*(u8 *)rxbuf = data;
else
*(u16 *)rxbuf = data;
rxbuf += wsize;
}
}
len -= count * wsize;
}
m->actual_length += t->len;
if (t->delay_usecs)
udelay(t->delay_usecs);
if (!cs_change)
continue;
if (t->transfer_list.next == &m->transfers)
break;
/* sometimes a short mid-message deselect of the chip
* may be needed to terminate a mode or command
*/
txx9spi_cs_func(spi, c, 0, cs_delay);
}
exit:
m->status = status;
if (m->complete)
m->complete(m->context);
/* normally deactivate chipselect ... unless no error and
* cs_change has hinted that the next message will probably
* be for this chip too.
*/
if (!(status == 0 && cs_change))
txx9spi_cs_func(spi, c, 0, cs_delay);
/* enter config mode */
txx9spi_wr(c, mcr | TXx9_SPMCR_CONFIG | TXx9_SPMCR_BCLR, TXx9_SPMCR);
}
static void txx9spi_work(struct work_struct *work)
{
struct txx9spi *c = container_of(work, struct txx9spi, work);
unsigned long flags;
spin_lock_irqsave(&c->lock, flags);
while (!list_empty(&c->queue)) {
struct spi_message *m;
m = container_of(c->queue.next, struct spi_message, queue);
list_del_init(&m->queue);
spin_unlock_irqrestore(&c->lock, flags);
txx9spi_work_one(c, m);
spin_lock_irqsave(&c->lock, flags);
}
spin_unlock_irqrestore(&c->lock, flags);
}
static int txx9spi_transfer(struct spi_device *spi, struct spi_message *m)
{
struct spi_master *master = spi->master;
struct txx9spi *c = spi_master_get_devdata(master);
struct spi_transfer *t;
unsigned long flags;
m->actual_length = 0;
/* check each transfer's parameters */
list_for_each_entry(t, &m->transfers, transfer_list) {
if (!t->tx_buf && !t->rx_buf && t->len)
return -EINVAL;
}
spin_lock_irqsave(&c->lock, flags);
list_add_tail(&m->queue, &c->queue);
schedule_work(&c->work);
spin_unlock_irqrestore(&c->lock, flags);
return 0;
}
static int txx9spi_probe(struct platform_device *dev)
{
struct spi_master *master;
struct txx9spi *c;
struct resource *res;
int ret = -ENODEV;
u32 mcr;
int irq;
master = spi_alloc_master(&dev->dev, sizeof(*c));
if (!master)
return ret;
c = spi_master_get_devdata(master);
platform_set_drvdata(dev, master);
INIT_WORK(&c->work, txx9spi_work);
spin_lock_init(&c->lock);
INIT_LIST_HEAD(&c->queue);
init_waitqueue_head(&c->waitq);
c->clk = devm_clk_get(&dev->dev, "spi-baseclk");
if (IS_ERR(c->clk)) {
ret = PTR_ERR(c->clk);
c->clk = NULL;
goto exit;
}
ret = clk_enable(c->clk);
if (ret) {
c->clk = NULL;
goto exit;
}
c->baseclk = clk_get_rate(c->clk);
master->min_speed_hz = DIV_ROUND_UP(c->baseclk, SPI_MAX_DIVIDER + 1);
master->max_speed_hz = c->baseclk / (SPI_MIN_DIVIDER + 1);
res = platform_get_resource(dev, IORESOURCE_MEM, 0);
c->membase = devm_ioremap_resource(&dev->dev, res);
if (IS_ERR(c->membase))
goto exit_busy;
/* enter config mode */
mcr = txx9spi_rd(c, TXx9_SPMCR);
mcr &= ~(TXx9_SPMCR_OPMODE | TXx9_SPMCR_SPSTP | TXx9_SPMCR_BCLR);
txx9spi_wr(c, mcr | TXx9_SPMCR_CONFIG | TXx9_SPMCR_BCLR, TXx9_SPMCR);
irq = platform_get_irq(dev, 0);
if (irq < 0)
goto exit_busy;
ret = devm_request_irq(&dev->dev, irq, txx9spi_interrupt, 0,
"spi_txx9", c);
if (ret)
goto exit;
c->last_chipselect = -1;
dev_info(&dev->dev, "at %#llx, irq %d, %dMHz\n",
(unsigned long long)res->start, irq,
(c->baseclk + 500000) / 1000000);
/* the spi->mode bits understood by this driver: */
master->mode_bits = SPI_CS_HIGH | SPI_CPOL | SPI_CPHA;
master->bus_num = dev->id;
master->setup = txx9spi_setup;
master->transfer = txx9spi_transfer;
master->num_chipselect = (u16)UINT_MAX; /* any GPIO numbers */
master->bits_per_word_mask = SPI_BPW_MASK(8) | SPI_BPW_MASK(16);
ret = devm_spi_register_master(&dev->dev, master);
if (ret)
goto exit;
return 0;
exit_busy:
ret = -EBUSY;
exit:
clk_disable(c->clk);
spi_master_put(master);
return ret;
}
static int txx9spi_remove(struct platform_device *dev)
{
struct spi_master *master = platform_get_drvdata(dev);
struct txx9spi *c = spi_master_get_devdata(master);
flush_work(&c->work);
clk_disable(c->clk);
return 0;
}
/* work with hotplug and coldplug */
MODULE_ALIAS("platform:spi_txx9");
static struct platform_driver txx9spi_driver = {
.probe = txx9spi_probe,
.remove = txx9spi_remove,
.driver = {
.name = "spi_txx9",
},
};
static int __init txx9spi_init(void)
{
return platform_driver_register(&txx9spi_driver);
}
subsys_initcall(txx9spi_init);
static void __exit txx9spi_exit(void)
{
platform_driver_unregister(&txx9spi_driver);
}
module_exit(txx9spi_exit);
MODULE_DESCRIPTION("TXx9 SPI Driver");
MODULE_LICENSE("GPL");
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