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linux-next/drivers/i2c/busses/i2c-sh_mobile.c
Magnus Damm 4eb00c9f92 i2c: fix i2c-sh_mobile timing issues 
This patch teaches the i2c-sh_mobile driver to make use of wait irqs.
Without this patch only dte irqs are used which may lead to overruns
and cases of missing stop and extra bytes being read on the i2c bus.

Use of wait irqs forces the hardware to pause and wait until the cpu
is ready. Polling is also reworked in this patch to fix ms delay issues.

Verified with bus analyzer and tested on MigoR and AP325RXA boards.

Signed-off-by: Magnus Damm <damm@igel.co.jp>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2008-09-05 14:54:13 +09:00

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/*
* SuperH Mobile I2C Controller
*
* Copyright (C) 2008 Magnus Damm
*
* Portions of the code based on out-of-tree driver i2c-sh7343.c
* Copyright (c) 2006 Carlos Munoz <carlos@kenati.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/platform_device.h>
#include <linux/interrupt.h>
#include <linux/i2c.h>
#include <linux/err.h>
#include <linux/clk.h>
#include <linux/io.h>
/* Transmit operation: */
/* */
/* 0 byte transmit */
/* BUS: S A8 ACK P */
/* IRQ: DTE WAIT */
/* ICIC: */
/* ICCR: 0x94 0x90 */
/* ICDR: A8 */
/* */
/* 1 byte transmit */
/* BUS: S A8 ACK D8(1) ACK P */
/* IRQ: DTE WAIT WAIT */
/* ICIC: -DTE */
/* ICCR: 0x94 0x90 */
/* ICDR: A8 D8(1) */
/* */
/* 2 byte transmit */
/* BUS: S A8 ACK D8(1) ACK D8(2) ACK P */
/* IRQ: DTE WAIT WAIT WAIT */
/* ICIC: -DTE */
/* ICCR: 0x94 0x90 */
/* ICDR: A8 D8(1) D8(2) */
/* */
/* 3 bytes or more, +---------+ gets repeated */
/* */
/* */
/* Receive operation: */
/* */
/* 0 byte receive - not supported since slave may hold SDA low */
/* */
/* 1 byte receive [TX] | [RX] */
/* BUS: S A8 ACK | D8(1) ACK P */
/* IRQ: DTE WAIT | WAIT DTE */
/* ICIC: -DTE | +DTE */
/* ICCR: 0x94 0x81 | 0xc0 */
/* ICDR: A8 | D8(1) */
/* */
/* 2 byte receive [TX]| [RX] */
/* BUS: S A8 ACK | D8(1) ACK D8(2) ACK P */
/* IRQ: DTE WAIT | WAIT WAIT DTE */
/* ICIC: -DTE | +DTE */
/* ICCR: 0x94 0x81 | 0xc0 */
/* ICDR: A8 | D8(1) D8(2) */
/* */
/* 3 byte receive [TX] | [RX] */
/* BUS: S A8 ACK | D8(1) ACK D8(2) ACK D8(3) ACK P */
/* IRQ: DTE WAIT | WAIT WAIT WAIT DTE */
/* ICIC: -DTE | +DTE */
/* ICCR: 0x94 0x81 | 0xc0 */
/* ICDR: A8 | D8(1) D8(2) D8(3) */
/* */
/* 4 bytes or more, this part is repeated +---------+ */
/* */
/* */
/* Interrupt order and BUSY flag */
/* ___ _ */
/* SDA ___\___XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXAAAAAAAAA___/ */
/* SCL \_/1\_/2\_/3\_/4\_/5\_/6\_/7\_/8\___/9\_____/ */
/* */
/* S D7 D6 D5 D4 D3 D2 D1 D0 P */
/* ___ */
/* WAIT IRQ ________________________________/ \___________ */
/* TACK IRQ ____________________________________/ \_______ */
/* DTE IRQ __________________________________________/ \_ */
/* AL IRQ XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX */
/* _______________________________________________ */
/* BUSY __/ \_ */
/* */
enum sh_mobile_i2c_op {
OP_START = 0,
OP_TX_FIRST,
OP_TX,
OP_TX_STOP,
OP_TX_TO_RX,
OP_RX,
OP_RX_STOP,
OP_RX_STOP_DATA,
};
struct sh_mobile_i2c_data {
struct device *dev;
void __iomem *reg;
struct i2c_adapter adap;
struct clk *clk;
u_int8_t iccl;
u_int8_t icch;
spinlock_t lock;
wait_queue_head_t wait;
struct i2c_msg *msg;
int pos;
int sr;
};
#define NORMAL_SPEED 100000 /* FAST_SPEED 400000 */
/* Register offsets */
#define ICDR(pd) (pd->reg + 0x00)
#define ICCR(pd) (pd->reg + 0x04)
#define ICSR(pd) (pd->reg + 0x08)
#define ICIC(pd) (pd->reg + 0x0c)
#define ICCL(pd) (pd->reg + 0x10)
#define ICCH(pd) (pd->reg + 0x14)
/* Register bits */
#define ICCR_ICE 0x80
#define ICCR_RACK 0x40
#define ICCR_TRS 0x10
#define ICCR_BBSY 0x04
#define ICCR_SCP 0x01
#define ICSR_SCLM 0x80
#define ICSR_SDAM 0x40
#define SW_DONE 0x20
#define ICSR_BUSY 0x10
#define ICSR_AL 0x08
#define ICSR_TACK 0x04
#define ICSR_WAIT 0x02
#define ICSR_DTE 0x01
#define ICIC_ALE 0x08
#define ICIC_TACKE 0x04
#define ICIC_WAITE 0x02
#define ICIC_DTEE 0x01
static void activate_ch(struct sh_mobile_i2c_data *pd)
{
/* Make sure the clock is enabled */
clk_enable(pd->clk);
/* Enable channel and configure rx ack */
iowrite8(ioread8(ICCR(pd)) | ICCR_ICE, ICCR(pd));
/* Mask all interrupts */
iowrite8(0, ICIC(pd));
/* Set the clock */
iowrite8(pd->iccl, ICCL(pd));
iowrite8(pd->icch, ICCH(pd));
}
static void deactivate_ch(struct sh_mobile_i2c_data *pd)
{
/* Clear/disable interrupts */
iowrite8(0, ICSR(pd));
iowrite8(0, ICIC(pd));
/* Disable channel */
iowrite8(ioread8(ICCR(pd)) & ~ICCR_ICE, ICCR(pd));
/* Disable clock */
clk_disable(pd->clk);
}
static unsigned char i2c_op(struct sh_mobile_i2c_data *pd,
enum sh_mobile_i2c_op op, unsigned char data)
{
unsigned char ret = 0;
unsigned long flags;
dev_dbg(pd->dev, "op %d, data in 0x%02x\n", op, data);
spin_lock_irqsave(&pd->lock, flags);
switch (op) {
case OP_START: /* issue start and trigger DTE interrupt */
iowrite8(0x94, ICCR(pd));
break;
case OP_TX_FIRST: /* disable DTE interrupt and write data */
iowrite8(ICIC_WAITE | ICIC_ALE | ICIC_TACKE, ICIC(pd));
iowrite8(data, ICDR(pd));
break;
case OP_TX: /* write data */
iowrite8(data, ICDR(pd));
break;
case OP_TX_STOP: /* write data and issue a stop afterwards */
iowrite8(data, ICDR(pd));
iowrite8(0x90, ICCR(pd));
break;
case OP_TX_TO_RX: /* select read mode */
iowrite8(0x81, ICCR(pd));
break;
case OP_RX: /* just read data */
ret = ioread8(ICDR(pd));
break;
case OP_RX_STOP: /* enable DTE interrupt, issue stop */
iowrite8(ICIC_DTEE | ICIC_WAITE | ICIC_ALE | ICIC_TACKE,
ICIC(pd));
iowrite8(0xc0, ICCR(pd));
break;
case OP_RX_STOP_DATA: /* enable DTE interrupt, read data, issue stop */
iowrite8(ICIC_DTEE | ICIC_WAITE | ICIC_ALE | ICIC_TACKE,
ICIC(pd));
ret = ioread8(ICDR(pd));
iowrite8(0xc0, ICCR(pd));
break;
}
spin_unlock_irqrestore(&pd->lock, flags);
dev_dbg(pd->dev, "op %d, data out 0x%02x\n", op, ret);
return ret;
}
static int sh_mobile_i2c_is_first_byte(struct sh_mobile_i2c_data *pd)
{
if (pd->pos == -1)
return 1;
return 0;
}
static int sh_mobile_i2c_is_last_byte(struct sh_mobile_i2c_data *pd)
{
if (pd->pos == (pd->msg->len - 1))
return 1;
return 0;
}
static void sh_mobile_i2c_get_data(struct sh_mobile_i2c_data *pd,
unsigned char *buf)
{
switch (pd->pos) {
case -1:
*buf = (pd->msg->addr & 0x7f) << 1;
*buf |= (pd->msg->flags & I2C_M_RD) ? 1 : 0;
break;
default:
*buf = pd->msg->buf[pd->pos];
}
}
static int sh_mobile_i2c_isr_tx(struct sh_mobile_i2c_data *pd)
{
unsigned char data;
if (pd->pos == pd->msg->len)
return 1;
sh_mobile_i2c_get_data(pd, &data);
if (sh_mobile_i2c_is_last_byte(pd))
i2c_op(pd, OP_TX_STOP, data);
else if (sh_mobile_i2c_is_first_byte(pd))
i2c_op(pd, OP_TX_FIRST, data);
else
i2c_op(pd, OP_TX, data);
pd->pos++;
return 0;
}
static int sh_mobile_i2c_isr_rx(struct sh_mobile_i2c_data *pd)
{
unsigned char data;
int real_pos;
do {
if (pd->pos <= -1) {
sh_mobile_i2c_get_data(pd, &data);
if (sh_mobile_i2c_is_first_byte(pd))
i2c_op(pd, OP_TX_FIRST, data);
else
i2c_op(pd, OP_TX, data);
break;
}
if (pd->pos == 0) {
i2c_op(pd, OP_TX_TO_RX, 0);
break;
}
real_pos = pd->pos - 2;
if (pd->pos == pd->msg->len) {
if (real_pos < 0) {
i2c_op(pd, OP_RX_STOP, 0);
break;
}
data = i2c_op(pd, OP_RX_STOP_DATA, 0);
} else
data = i2c_op(pd, OP_RX, 0);
pd->msg->buf[real_pos] = data;
} while (0);
pd->pos++;
return pd->pos == (pd->msg->len + 2);
}
static irqreturn_t sh_mobile_i2c_isr(int irq, void *dev_id)
{
struct platform_device *dev = dev_id;
struct sh_mobile_i2c_data *pd = platform_get_drvdata(dev);
unsigned char sr;
int wakeup;
sr = ioread8(ICSR(pd));
pd->sr |= sr; /* remember state */
dev_dbg(pd->dev, "i2c_isr 0x%02x 0x%02x %s %d %d!\n", sr, pd->sr,
(pd->msg->flags & I2C_M_RD) ? "read" : "write",
pd->pos, pd->msg->len);
if (sr & (ICSR_AL | ICSR_TACK)) {
/* don't interrupt transaction - continue to issue stop */
iowrite8(sr & ~(ICSR_AL | ICSR_TACK), ICSR(pd));
wakeup = 0;
} else if (pd->msg->flags & I2C_M_RD)
wakeup = sh_mobile_i2c_isr_rx(pd);
else
wakeup = sh_mobile_i2c_isr_tx(pd);
if (sr & ICSR_WAIT) /* TODO: add delay here to support slow acks */
iowrite8(sr & ~ICSR_WAIT, ICSR(pd));
if (wakeup) {
pd->sr |= SW_DONE;
wake_up(&pd->wait);
}
return IRQ_HANDLED;
}
static int start_ch(struct sh_mobile_i2c_data *pd, struct i2c_msg *usr_msg)
{
if (usr_msg->len == 0 && (usr_msg->flags & I2C_M_RD)) {
dev_err(pd->dev, "Unsupported zero length i2c read\n");
return -EIO;
}
/* Initialize channel registers */
iowrite8(ioread8(ICCR(pd)) & ~ICCR_ICE, ICCR(pd));
/* Enable channel and configure rx ack */
iowrite8(ioread8(ICCR(pd)) | ICCR_ICE, ICCR(pd));
/* Set the clock */
iowrite8(pd->iccl, ICCL(pd));
iowrite8(pd->icch, ICCH(pd));
pd->msg = usr_msg;
pd->pos = -1;
pd->sr = 0;
/* Enable all interrupts to begin with */
iowrite8(ICIC_WAITE | ICIC_ALE | ICIC_TACKE | ICIC_DTEE, ICIC(pd));
return 0;
}
static int sh_mobile_i2c_xfer(struct i2c_adapter *adapter,
struct i2c_msg *msgs,
int num)
{
struct sh_mobile_i2c_data *pd = i2c_get_adapdata(adapter);
struct i2c_msg *msg;
int err = 0;
u_int8_t val;
int i, k, retry_count;
activate_ch(pd);
/* Process all messages */
for (i = 0; i < num; i++) {
msg = &msgs[i];
err = start_ch(pd, msg);
if (err)
break;
i2c_op(pd, OP_START, 0);
/* The interrupt handler takes care of the rest... */
k = wait_event_timeout(pd->wait,
pd->sr & (ICSR_TACK | SW_DONE),
5 * HZ);
if (!k)
dev_err(pd->dev, "Transfer request timed out\n");
retry_count = 1000;
again:
val = ioread8(ICSR(pd));
dev_dbg(pd->dev, "val 0x%02x pd->sr 0x%02x\n", val, pd->sr);
/* the interrupt handler may wake us up before the
* transfer is finished, so poll the hardware
* until we're done.
*/
if (val & ICSR_BUSY) {
udelay(10);
if (retry_count--)
goto again;
err = -EIO;
dev_err(pd->dev, "Polling timed out\n");
break;
}
/* handle missing acknowledge and arbitration lost */
if ((val | pd->sr) & (ICSR_TACK | ICSR_AL)) {
err = -EIO;
break;
}
}
deactivate_ch(pd);
if (!err)
err = num;
return err;
}
static u32 sh_mobile_i2c_func(struct i2c_adapter *adapter)
{
return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
}
static struct i2c_algorithm sh_mobile_i2c_algorithm = {
.functionality = sh_mobile_i2c_func,
.master_xfer = sh_mobile_i2c_xfer,
};
static void sh_mobile_i2c_setup_channel(struct platform_device *dev)
{
struct sh_mobile_i2c_data *pd = platform_get_drvdata(dev);
unsigned long peripheral_clk = clk_get_rate(pd->clk);
u_int32_t num;
u_int32_t denom;
u_int32_t tmp;
spin_lock_init(&pd->lock);
init_waitqueue_head(&pd->wait);
/* Calculate the value for iccl. From the data sheet:
* iccl = (p clock / transfer rate) * (L / (L + H))
* where L and H are the SCL low/high ratio (5/4 in this case).
* We also round off the result.
*/
num = peripheral_clk * 5;
denom = NORMAL_SPEED * 9;
tmp = num * 10 / denom;
if (tmp % 10 >= 5)
pd->iccl = (u_int8_t)((num/denom) + 1);
else
pd->iccl = (u_int8_t)(num/denom);
/* Calculate the value for icch. From the data sheet:
icch = (p clock / transfer rate) * (H / (L + H)) */
num = peripheral_clk * 4;
tmp = num * 10 / denom;
if (tmp % 10 >= 5)
pd->icch = (u_int8_t)((num/denom) + 1);
else
pd->icch = (u_int8_t)(num/denom);
}
static int sh_mobile_i2c_hook_irqs(struct platform_device *dev, int hook)
{
struct resource *res;
int ret = -ENXIO;
int q, m;
int k = 0;
int n = 0;
while ((res = platform_get_resource(dev, IORESOURCE_IRQ, k))) {
for (n = res->start; hook && n <= res->end; n++) {
if (request_irq(n, sh_mobile_i2c_isr, IRQF_DISABLED,
dev->dev.bus_id, dev))
goto rollback;
}
k++;
}
if (hook)
return k > 0 ? 0 : -ENOENT;
k--;
ret = 0;
rollback:
for (q = k; k >= 0; k--) {
for (m = n; m >= res->start; m--)
free_irq(m, dev);
res = platform_get_resource(dev, IORESOURCE_IRQ, k - 1);
m = res->end;
}
return ret;
}
static int sh_mobile_i2c_probe(struct platform_device *dev)
{
struct sh_mobile_i2c_data *pd;
struct i2c_adapter *adap;
struct resource *res;
int size;
int ret;
pd = kzalloc(sizeof(struct sh_mobile_i2c_data), GFP_KERNEL);
if (pd == NULL) {
dev_err(&dev->dev, "cannot allocate private data\n");
return -ENOMEM;
}
pd->clk = clk_get(&dev->dev, "peripheral_clk");
if (IS_ERR(pd->clk)) {
dev_err(&dev->dev, "cannot get peripheral clock\n");
ret = PTR_ERR(pd->clk);
goto err;
}
ret = sh_mobile_i2c_hook_irqs(dev, 1);
if (ret) {
dev_err(&dev->dev, "cannot request IRQ\n");
goto err_clk;
}
pd->dev = &dev->dev;
platform_set_drvdata(dev, pd);
res = platform_get_resource(dev, IORESOURCE_MEM, 0);
if (res == NULL) {
dev_err(&dev->dev, "cannot find IO resource\n");
ret = -ENOENT;
goto err_irq;
}
size = (res->end - res->start) + 1;
pd->reg = ioremap(res->start, size);
if (pd->reg == NULL) {
dev_err(&dev->dev, "cannot map IO\n");
ret = -ENXIO;
goto err_irq;
}
/* setup the private data */
adap = &pd->adap;
i2c_set_adapdata(adap, pd);
adap->owner = THIS_MODULE;
adap->algo = &sh_mobile_i2c_algorithm;
adap->dev.parent = &dev->dev;
adap->retries = 5;
adap->nr = dev->id;
strlcpy(adap->name, dev->name, sizeof(adap->name));
sh_mobile_i2c_setup_channel(dev);
ret = i2c_add_numbered_adapter(adap);
if (ret < 0) {
dev_err(&dev->dev, "cannot add numbered adapter\n");
goto err_all;
}
return 0;
err_all:
iounmap(pd->reg);
err_irq:
sh_mobile_i2c_hook_irqs(dev, 0);
err_clk:
clk_put(pd->clk);
err:
kfree(pd);
return ret;
}
static int sh_mobile_i2c_remove(struct platform_device *dev)
{
struct sh_mobile_i2c_data *pd = platform_get_drvdata(dev);
i2c_del_adapter(&pd->adap);
iounmap(pd->reg);
sh_mobile_i2c_hook_irqs(dev, 0);
clk_put(pd->clk);
kfree(pd);
return 0;
}
static struct platform_driver sh_mobile_i2c_driver = {
.driver = {
.name = "i2c-sh_mobile",
.owner = THIS_MODULE,
},
.probe = sh_mobile_i2c_probe,
.remove = sh_mobile_i2c_remove,
};
static int __init sh_mobile_i2c_adap_init(void)
{
return platform_driver_register(&sh_mobile_i2c_driver);
}
static void __exit sh_mobile_i2c_adap_exit(void)
{
platform_driver_unregister(&sh_mobile_i2c_driver);
}
module_init(sh_mobile_i2c_adap_init);
module_exit(sh_mobile_i2c_adap_exit);
MODULE_DESCRIPTION("SuperH Mobile I2C Bus Controller driver");
MODULE_AUTHOR("Magnus Damm");
MODULE_LICENSE("GPL v2");
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