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linux/drivers/w1/masters/ds1wm.c
David Fries c30c9b1518 W1: fix deadlocks and remove w1_control_thread 
w1_control_thread was removed which would wake up every second and process
newly registered family codes and complete some final cleanup for a
removed master.  Those routines were moved to the threads that were
previously requesting those operations.  A new function
w1_reconnect_slaves takes care of reconnecting existing slave devices when
a new family code is registered or removed.  The removal case was missing
and would cause a deadlock waiting for the family code reference count to
decrease, which will now happen.  A problem with registering a family code
was fixed.  A slave device would be unattached if it wasn't yet claimed,
then attached at the end of the list, two unclaimed slaves would cause an
infinite loop.

The struct w1_bus_master.search now takes a pointer to the struct
w1_master device to avoid searching for it, which would have caused a
lock ordering deadlock with the removal of w1_control_thread.

Signed-off-by: David Fries <david@fries.net>
Signed-off-by: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-10-16 11:21:49 -07:00

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/*
* 1-wire busmaster driver for DS1WM and ASICs with embedded DS1WMs
* such as HP iPAQs (including h5xxx, h2200, and devices with ASIC3
* like hx4700).
*
* Copyright (c) 2004-2005, Szabolcs Gyurko <szabolcs.gyurko@tlt.hu>
* Copyright (c) 2004-2007, Matt Reimer <mreimer@vpop.net>
*
* Use consistent with the GNU GPL is permitted,
* provided that this copyright notice is
* preserved in its entirety in all copies and derived works.
*/
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/pm.h>
#include <linux/platform_device.h>
#include <linux/clk.h>
#include <linux/err.h>
#include <linux/delay.h>
#include <linux/ds1wm.h>
#include <asm/io.h>
#include "../w1.h"
#include "../w1_int.h"
#define DS1WM_CMD 0x00 /* R/W 4 bits command */
#define DS1WM_DATA 0x01 /* R/W 8 bits, transmit/receive buffer */
#define DS1WM_INT 0x02 /* R/W interrupt status */
#define DS1WM_INT_EN 0x03 /* R/W interrupt enable */
#define DS1WM_CLKDIV 0x04 /* R/W 5 bits of divisor and pre-scale */
#define DS1WM_CMD_1W_RESET (1 << 0) /* force reset on 1-wire bus */
#define DS1WM_CMD_SRA (1 << 1) /* enable Search ROM accelerator mode */
#define DS1WM_CMD_DQ_OUTPUT (1 << 2) /* write only - forces bus low */
#define DS1WM_CMD_DQ_INPUT (1 << 3) /* read only - reflects state of bus */
#define DS1WM_CMD_RST (1 << 5) /* software reset */
#define DS1WM_CMD_OD (1 << 7) /* overdrive */
#define DS1WM_INT_PD (1 << 0) /* presence detect */
#define DS1WM_INT_PDR (1 << 1) /* presence detect result */
#define DS1WM_INT_TBE (1 << 2) /* tx buffer empty */
#define DS1WM_INT_TSRE (1 << 3) /* tx shift register empty */
#define DS1WM_INT_RBF (1 << 4) /* rx buffer full */
#define DS1WM_INT_RSRF (1 << 5) /* rx shift register full */
#define DS1WM_INTEN_EPD (1 << 0) /* enable presence detect int */
#define DS1WM_INTEN_IAS (1 << 1) /* INTR active state */
#define DS1WM_INTEN_ETBE (1 << 2) /* enable tx buffer empty int */
#define DS1WM_INTEN_ETMT (1 << 3) /* enable tx shift register empty int */
#define DS1WM_INTEN_ERBF (1 << 4) /* enable rx buffer full int */
#define DS1WM_INTEN_ERSRF (1 << 5) /* enable rx shift register full int */
#define DS1WM_INTEN_DQO (1 << 6) /* enable direct bus driving ops */
#define DS1WM_TIMEOUT (HZ * 5)
static struct {
unsigned long freq;
unsigned long divisor;
} freq[] = {
{ 4000000, 0x8 },
{ 5000000, 0x2 },
{ 6000000, 0x5 },
{ 7000000, 0x3 },
{ 8000000, 0xc },
{ 10000000, 0x6 },
{ 12000000, 0x9 },
{ 14000000, 0x7 },
{ 16000000, 0x10 },
{ 20000000, 0xa },
{ 24000000, 0xd },
{ 28000000, 0xb },
{ 32000000, 0x14 },
{ 40000000, 0xe },
{ 48000000, 0x11 },
{ 56000000, 0xf },
{ 64000000, 0x18 },
{ 80000000, 0x12 },
{ 96000000, 0x15 },
{ 112000000, 0x13 },
{ 128000000, 0x1c },
};
struct ds1wm_data {
void __iomem *map;
int bus_shift; /* # of shifts to calc register offsets */
struct platform_device *pdev;
struct ds1wm_platform_data *pdata;
int irq;
int active_high;
struct clk *clk;
int slave_present;
void *reset_complete;
void *read_complete;
void *write_complete;
u8 read_byte; /* last byte received */
};
static inline void ds1wm_write_register(struct ds1wm_data *ds1wm_data, u32 reg,
u8 val)
{
__raw_writeb(val, ds1wm_data->map + (reg << ds1wm_data->bus_shift));
}
static inline u8 ds1wm_read_register(struct ds1wm_data *ds1wm_data, u32 reg)
{
return __raw_readb(ds1wm_data->map + (reg << ds1wm_data->bus_shift));
}
static irqreturn_t ds1wm_isr(int isr, void *data)
{
struct ds1wm_data *ds1wm_data = data;
u8 intr = ds1wm_read_register(ds1wm_data, DS1WM_INT);
ds1wm_data->slave_present = (intr & DS1WM_INT_PDR) ? 0 : 1;
if ((intr & DS1WM_INT_PD) && ds1wm_data->reset_complete)
complete(ds1wm_data->reset_complete);
if ((intr & DS1WM_INT_TSRE) && ds1wm_data->write_complete)
complete(ds1wm_data->write_complete);
if (intr & DS1WM_INT_RBF) {
ds1wm_data->read_byte = ds1wm_read_register(ds1wm_data,
DS1WM_DATA);
if (ds1wm_data->read_complete)
complete(ds1wm_data->read_complete);
}
return IRQ_HANDLED;
}
static int ds1wm_reset(struct ds1wm_data *ds1wm_data)
{
unsigned long timeleft;
DECLARE_COMPLETION_ONSTACK(reset_done);
ds1wm_data->reset_complete = &reset_done;
ds1wm_write_register(ds1wm_data, DS1WM_INT_EN, DS1WM_INTEN_EPD |
(ds1wm_data->active_high ? DS1WM_INTEN_IAS : 0));
ds1wm_write_register(ds1wm_data, DS1WM_CMD, DS1WM_CMD_1W_RESET);
timeleft = wait_for_completion_timeout(&reset_done, DS1WM_TIMEOUT);
ds1wm_data->reset_complete = NULL;
if (!timeleft) {
dev_err(&ds1wm_data->pdev->dev, "reset failed\n");
return 1;
}
/* Wait for the end of the reset. According to the specs, the time
* from when the interrupt is asserted to the end of the reset is:
* tRSTH - tPDH - tPDL - tPDI
* 625 us - 60 us - 240 us - 100 ns = 324.9 us
*
* We'll wait a bit longer just to be sure.
*/
udelay(500);
ds1wm_write_register(ds1wm_data, DS1WM_INT_EN,
DS1WM_INTEN_ERBF | DS1WM_INTEN_ETMT | DS1WM_INTEN_EPD |
(ds1wm_data->active_high ? DS1WM_INTEN_IAS : 0));
if (!ds1wm_data->slave_present) {
dev_dbg(&ds1wm_data->pdev->dev, "reset: no devices found\n");
return 1;
}
return 0;
}
static int ds1wm_write(struct ds1wm_data *ds1wm_data, u8 data)
{
DECLARE_COMPLETION_ONSTACK(write_done);
ds1wm_data->write_complete = &write_done;
ds1wm_write_register(ds1wm_data, DS1WM_DATA, data);
wait_for_completion_timeout(&write_done, DS1WM_TIMEOUT);
ds1wm_data->write_complete = NULL;
return 0;
}
static int ds1wm_read(struct ds1wm_data *ds1wm_data, unsigned char write_data)
{
DECLARE_COMPLETION_ONSTACK(read_done);
ds1wm_data->read_complete = &read_done;
ds1wm_write(ds1wm_data, write_data);
wait_for_completion_timeout(&read_done, DS1WM_TIMEOUT);
ds1wm_data->read_complete = NULL;
return ds1wm_data->read_byte;
}
static int ds1wm_find_divisor(int gclk)
{
int i;
for (i = 0; i < ARRAY_SIZE(freq); i++)
if (gclk <= freq[i].freq)
return freq[i].divisor;
return 0;
}
static void ds1wm_up(struct ds1wm_data *ds1wm_data)
{
int gclk, divisor;
if (ds1wm_data->pdata->enable)
ds1wm_data->pdata->enable(ds1wm_data->pdev);
gclk = clk_get_rate(ds1wm_data->clk);
clk_enable(ds1wm_data->clk);
divisor = ds1wm_find_divisor(gclk);
if (divisor == 0) {
dev_err(&ds1wm_data->pdev->dev,
"no suitable divisor for %dHz clock\n", gclk);
return;
}
ds1wm_write_register(ds1wm_data, DS1WM_CLKDIV, divisor);
/* Let the w1 clock stabilize. */
msleep(1);
ds1wm_reset(ds1wm_data);
}
static void ds1wm_down(struct ds1wm_data *ds1wm_data)
{
ds1wm_reset(ds1wm_data);
/* Disable interrupts. */
ds1wm_write_register(ds1wm_data, DS1WM_INT_EN,
ds1wm_data->active_high ? DS1WM_INTEN_IAS : 0);
if (ds1wm_data->pdata->disable)
ds1wm_data->pdata->disable(ds1wm_data->pdev);
clk_disable(ds1wm_data->clk);
}
/* --------------------------------------------------------------------- */
/* w1 methods */
static u8 ds1wm_read_byte(void *data)
{
struct ds1wm_data *ds1wm_data = data;
return ds1wm_read(ds1wm_data, 0xff);
}
static void ds1wm_write_byte(void *data, u8 byte)
{
struct ds1wm_data *ds1wm_data = data;
ds1wm_write(ds1wm_data, byte);
}
static u8 ds1wm_reset_bus(void *data)
{
struct ds1wm_data *ds1wm_data = data;
ds1wm_reset(ds1wm_data);
return 0;
}
static void ds1wm_search(void *data, struct w1_master *master_dev,
u8 search_type, w1_slave_found_callback slave_found)
{
struct ds1wm_data *ds1wm_data = data;
int i;
unsigned long long rom_id;
/* XXX We need to iterate for multiple devices per the DS1WM docs.
* See http://www.maxim-ic.com/appnotes.cfm/appnote_number/120. */
if (ds1wm_reset(ds1wm_data))
return;
ds1wm_write(ds1wm_data, search_type);
ds1wm_write_register(ds1wm_data, DS1WM_CMD, DS1WM_CMD_SRA);
for (rom_id = 0, i = 0; i < 16; i++) {
unsigned char resp, r, d;
resp = ds1wm_read(ds1wm_data, 0x00);
r = ((resp & 0x02) >> 1) |
((resp & 0x08) >> 2) |
((resp & 0x20) >> 3) |
((resp & 0x80) >> 4);
d = ((resp & 0x01) >> 0) |
((resp & 0x04) >> 1) |
((resp & 0x10) >> 2) |
((resp & 0x40) >> 3);
rom_id |= (unsigned long long) r << (i * 4);
}
dev_dbg(&ds1wm_data->pdev->dev, "found 0x%08llX\n", rom_id);
ds1wm_write_register(ds1wm_data, DS1WM_CMD, ~DS1WM_CMD_SRA);
ds1wm_reset(ds1wm_data);
slave_found(master_dev, rom_id);
}
/* --------------------------------------------------------------------- */
static struct w1_bus_master ds1wm_master = {
.read_byte = ds1wm_read_byte,
.write_byte = ds1wm_write_byte,
.reset_bus = ds1wm_reset_bus,
.search = ds1wm_search,
};
static int ds1wm_probe(struct platform_device *pdev)
{
struct ds1wm_data *ds1wm_data;
struct ds1wm_platform_data *plat;
struct resource *res;
int ret;
if (!pdev)
return -ENODEV;
ds1wm_data = kzalloc(sizeof(*ds1wm_data), GFP_KERNEL);
if (!ds1wm_data)
return -ENOMEM;
platform_set_drvdata(pdev, ds1wm_data);
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (!res) {
ret = -ENXIO;
goto err0;
}
ds1wm_data->map = ioremap(res->start, res->end - res->start + 1);
if (!ds1wm_data->map) {
ret = -ENOMEM;
goto err0;
}
plat = pdev->dev.platform_data;
ds1wm_data->bus_shift = plat->bus_shift;
ds1wm_data->pdev = pdev;
ds1wm_data->pdata = plat;
res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
if (!res) {
ret = -ENXIO;
goto err1;
}
ds1wm_data->irq = res->start;
ds1wm_data->active_high = plat->active_high;
if (res->flags & IORESOURCE_IRQ_HIGHEDGE)
set_irq_type(ds1wm_data->irq, IRQ_TYPE_EDGE_RISING);
if (res->flags & IORESOURCE_IRQ_LOWEDGE)
set_irq_type(ds1wm_data->irq, IRQ_TYPE_EDGE_FALLING);
ret = request_irq(ds1wm_data->irq, ds1wm_isr, IRQF_DISABLED,
"ds1wm", ds1wm_data);
if (ret)
goto err1;
ds1wm_data->clk = clk_get(&pdev->dev, "ds1wm");
if (IS_ERR(ds1wm_data->clk)) {
ret = PTR_ERR(ds1wm_data->clk);
goto err2;
}
ds1wm_up(ds1wm_data);
ds1wm_master.data = (void *)ds1wm_data;
ret = w1_add_master_device(&ds1wm_master);
if (ret)
goto err3;
return 0;
err3:
ds1wm_down(ds1wm_data);
clk_put(ds1wm_data->clk);
err2:
free_irq(ds1wm_data->irq, ds1wm_data);
err1:
iounmap(ds1wm_data->map);
err0:
kfree(ds1wm_data);
return ret;
}
#ifdef CONFIG_PM
static int ds1wm_suspend(struct platform_device *pdev, pm_message_t state)
{
struct ds1wm_data *ds1wm_data = platform_get_drvdata(pdev);
ds1wm_down(ds1wm_data);
return 0;
}
static int ds1wm_resume(struct platform_device *pdev)
{
struct ds1wm_data *ds1wm_data = platform_get_drvdata(pdev);
ds1wm_up(ds1wm_data);
return 0;
}
#else
#define ds1wm_suspend NULL
#define ds1wm_resume NULL
#endif
static int ds1wm_remove(struct platform_device *pdev)
{
struct ds1wm_data *ds1wm_data = platform_get_drvdata(pdev);
w1_remove_master_device(&ds1wm_master);
ds1wm_down(ds1wm_data);
clk_put(ds1wm_data->clk);
free_irq(ds1wm_data->irq, ds1wm_data);
iounmap(ds1wm_data->map);
kfree(ds1wm_data);
return 0;
}
static struct platform_driver ds1wm_driver = {
.driver = {
.name = "ds1wm",
},
.probe = ds1wm_probe,
.remove = ds1wm_remove,
.suspend = ds1wm_suspend,
.resume = ds1wm_resume
};
static int __init ds1wm_init(void)
{
printk("DS1WM w1 busmaster driver - (c) 2004 Szabolcs Gyurko\n");
return platform_driver_register(&ds1wm_driver);
}
static void __exit ds1wm_exit(void)
{
platform_driver_unregister(&ds1wm_driver);
}
module_init(ds1wm_init);
module_exit(ds1wm_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Szabolcs Gyurko <szabolcs.gyurko@tlt.hu>, "
"Matt Reimer <mreimer@vpop.net>");
MODULE_DESCRIPTION("DS1WM w1 busmaster driver");
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