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linux/drivers/i2c/busses/i2c-octeon.c
Bernhard Walle cc33e54290 i2c-octeon: Return -ETIMEDOUT in octeon_i2c_wait() on timeout 
It doesn't make sense to set result to -ETIMEDOUT but return 0 (success)
afterwards. Since there's code in octeon_i2c_start() to handle the
error, it should be called.

Signed-off-by: Bernhard Walle <walle@corscience.de>
Acked-by: David Daney <ddaney@caviumnetworks.com>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>
2010-09-27 23:21:16 +01:00

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/*
* (C) Copyright 2009-2010
* Nokia Siemens Networks, michael.lawnick.ext@nsn.com
*
* Portions Copyright (C) 2010 Cavium Networks, Inc.
*
* This is a driver for the i2c adapter in Cavium Networks' OCTEON processors.
*
* 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.
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/i2c.h>
#include <linux/interrupt.h>
#include <linux/delay.h>
#include <linux/platform_device.h>
#include <asm/octeon/octeon.h>
#define DRV_NAME "i2c-octeon"
/* The previous out-of-tree version was implicitly version 1.0. */
#define DRV_VERSION "2.0"
/* register offsets */
#define SW_TWSI 0x00
#define TWSI_INT 0x10
/* Controller command patterns */
#define SW_TWSI_V 0x8000000000000000ull
#define SW_TWSI_EOP_TWSI_DATA 0x0C00000100000000ull
#define SW_TWSI_EOP_TWSI_CTL 0x0C00000200000000ull
#define SW_TWSI_EOP_TWSI_CLKCTL 0x0C00000300000000ull
#define SW_TWSI_EOP_TWSI_STAT 0x0C00000300000000ull
#define SW_TWSI_EOP_TWSI_RST 0x0C00000700000000ull
#define SW_TWSI_OP_TWSI_CLK 0x0800000000000000ull
#define SW_TWSI_R 0x0100000000000000ull
/* Controller command and status bits */
#define TWSI_CTL_CE 0x80
#define TWSI_CTL_ENAB 0x40
#define TWSI_CTL_STA 0x20
#define TWSI_CTL_STP 0x10
#define TWSI_CTL_IFLG 0x08
#define TWSI_CTL_AAK 0x04
/* Some status values */
#define STAT_START 0x08
#define STAT_RSTART 0x10
#define STAT_TXADDR_ACK 0x18
#define STAT_TXDATA_ACK 0x28
#define STAT_RXADDR_ACK 0x40
#define STAT_RXDATA_ACK 0x50
#define STAT_IDLE 0xF8
struct octeon_i2c {
wait_queue_head_t queue;
struct i2c_adapter adap;
int irq;
int twsi_freq;
int sys_freq;
resource_size_t twsi_phys;
void __iomem *twsi_base;
resource_size_t regsize;
struct device *dev;
};
/**
* octeon_i2c_write_sw - write an I2C core register.
* @i2c: The struct octeon_i2c.
* @eop_reg: Register selector.
* @data: Value to be written.
*
* The I2C core registers are accessed indirectly via the SW_TWSI CSR.
*/
static void octeon_i2c_write_sw(struct octeon_i2c *i2c,
u64 eop_reg,
u8 data)
{
u64 tmp;
__raw_writeq(SW_TWSI_V | eop_reg | data, i2c->twsi_base + SW_TWSI);
do {
tmp = __raw_readq(i2c->twsi_base + SW_TWSI);
} while ((tmp & SW_TWSI_V) != 0);
}
/**
* octeon_i2c_read_sw - write an I2C core register.
* @i2c: The struct octeon_i2c.
* @eop_reg: Register selector.
*
* Returns the data.
*
* The I2C core registers are accessed indirectly via the SW_TWSI CSR.
*/
static u8 octeon_i2c_read_sw(struct octeon_i2c *i2c, u64 eop_reg)
{
u64 tmp;
__raw_writeq(SW_TWSI_V | eop_reg | SW_TWSI_R, i2c->twsi_base + SW_TWSI);
do {
tmp = __raw_readq(i2c->twsi_base + SW_TWSI);
} while ((tmp & SW_TWSI_V) != 0);
return tmp & 0xFF;
}
/**
* octeon_i2c_write_int - write the TWSI_INT register
* @i2c: The struct octeon_i2c.
* @data: Value to be written.
*/
static void octeon_i2c_write_int(struct octeon_i2c *i2c, u64 data)
{
u64 tmp;
__raw_writeq(data, i2c->twsi_base + TWSI_INT);
tmp = __raw_readq(i2c->twsi_base + TWSI_INT);
}
/**
* octeon_i2c_int_enable - enable the TS interrupt.
* @i2c: The struct octeon_i2c.
*
* The interrupt will be asserted when there is non-STAT_IDLE state in
* the SW_TWSI_EOP_TWSI_STAT register.
*/
static void octeon_i2c_int_enable(struct octeon_i2c *i2c)
{
octeon_i2c_write_int(i2c, 0x40);
}
/**
* octeon_i2c_int_disable - disable the TS interrupt.
* @i2c: The struct octeon_i2c.
*/
static void octeon_i2c_int_disable(struct octeon_i2c *i2c)
{
octeon_i2c_write_int(i2c, 0);
}
/**
* octeon_i2c_unblock - unblock the bus.
* @i2c: The struct octeon_i2c.
*
* If there was a reset while a device was driving 0 to bus,
* bus is blocked. We toggle it free manually by some clock
* cycles and send a stop.
*/
static void octeon_i2c_unblock(struct octeon_i2c *i2c)
{
int i;
dev_dbg(i2c->dev, "%s\n", __func__);
for (i = 0; i < 9; i++) {
octeon_i2c_write_int(i2c, 0x0);
udelay(5);
octeon_i2c_write_int(i2c, 0x200);
udelay(5);
}
octeon_i2c_write_int(i2c, 0x300);
udelay(5);
octeon_i2c_write_int(i2c, 0x100);
udelay(5);
octeon_i2c_write_int(i2c, 0x0);
}
/**
* octeon_i2c_isr - the interrupt service routine.
* @int: The irq, unused.
* @dev_id: Our struct octeon_i2c.
*/
static irqreturn_t octeon_i2c_isr(int irq, void *dev_id)
{
struct octeon_i2c *i2c = dev_id;
octeon_i2c_int_disable(i2c);
wake_up_interruptible(&i2c->queue);
return IRQ_HANDLED;
}
static int octeon_i2c_test_iflg(struct octeon_i2c *i2c)
{
return (octeon_i2c_read_sw(i2c, SW_TWSI_EOP_TWSI_CTL) & TWSI_CTL_IFLG) != 0;
}
/**
* octeon_i2c_wait - wait for the IFLG to be set.
* @i2c: The struct octeon_i2c.
*
* Returns 0 on success, otherwise a negative errno.
*/
static int octeon_i2c_wait(struct octeon_i2c *i2c)
{
int result;
octeon_i2c_int_enable(i2c);
result = wait_event_interruptible_timeout(i2c->queue,
octeon_i2c_test_iflg(i2c),
i2c->adap.timeout);
octeon_i2c_int_disable(i2c);
if (result < 0) {
dev_dbg(i2c->dev, "%s: wait interrupted\n", __func__);
return result;
} else if (result == 0) {
dev_dbg(i2c->dev, "%s: timeout\n", __func__);
return -ETIMEDOUT;
}
return 0;
}
/**
* octeon_i2c_start - send START to the bus.
* @i2c: The struct octeon_i2c.
*
* Returns 0 on success, otherwise a negative errno.
*/
static int octeon_i2c_start(struct octeon_i2c *i2c)
{
u8 data;
int result;
octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL,
TWSI_CTL_ENAB | TWSI_CTL_STA);
result = octeon_i2c_wait(i2c);
if (result) {
if (octeon_i2c_read_sw(i2c, SW_TWSI_EOP_TWSI_STAT) == STAT_IDLE) {
/*
* Controller refused to send start flag May
* be a client is holding SDA low - let's try
* to free it.
*/
octeon_i2c_unblock(i2c);
octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL,
TWSI_CTL_ENAB | TWSI_CTL_STA);
result = octeon_i2c_wait(i2c);
}
if (result)
return result;
}
data = octeon_i2c_read_sw(i2c, SW_TWSI_EOP_TWSI_STAT);
if ((data != STAT_START) && (data != STAT_RSTART)) {
dev_err(i2c->dev, "%s: bad status (0x%x)\n", __func__, data);
return -EIO;
}
return 0;
}
/**
* octeon_i2c_stop - send STOP to the bus.
* @i2c: The struct octeon_i2c.
*
* Returns 0 on success, otherwise a negative errno.
*/
static int octeon_i2c_stop(struct octeon_i2c *i2c)
{
u8 data;
octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL,
TWSI_CTL_ENAB | TWSI_CTL_STP);
data = octeon_i2c_read_sw(i2c, SW_TWSI_EOP_TWSI_STAT);
if (data != STAT_IDLE) {
dev_err(i2c->dev, "%s: bad status(0x%x)\n", __func__, data);
return -EIO;
}
return 0;
}
/**
* octeon_i2c_write - send data to the bus.
* @i2c: The struct octeon_i2c.
* @target: Target address.
* @data: Pointer to the data to be sent.
* @length: Length of the data.
*
* The address is sent over the bus, then the data.
*
* Returns 0 on success, otherwise a negative errno.
*/
static int octeon_i2c_write(struct octeon_i2c *i2c, int target,
const u8 *data, int length)
{
int i, result;
u8 tmp;
result = octeon_i2c_start(i2c);
if (result)
return result;
octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_DATA, target << 1);
octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL, TWSI_CTL_ENAB);
result = octeon_i2c_wait(i2c);
if (result)
return result;
for (i = 0; i < length; i++) {
tmp = octeon_i2c_read_sw(i2c, SW_TWSI_EOP_TWSI_STAT);
if ((tmp != STAT_TXADDR_ACK) && (tmp != STAT_TXDATA_ACK)) {
dev_err(i2c->dev,
"%s: bad status before write (0x%x)\n",
__func__, tmp);
return -EIO;
}
octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_DATA, data[i]);
octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL, TWSI_CTL_ENAB);
result = octeon_i2c_wait(i2c);
if (result)
return result;
}
return 0;
}
/**
* octeon_i2c_read - receive data from the bus.
* @i2c: The struct octeon_i2c.
* @target: Target address.
* @data: Pointer to the location to store the datae .
* @length: Length of the data.
*
* The address is sent over the bus, then the data is read.
*
* Returns 0 on success, otherwise a negative errno.
*/
static int octeon_i2c_read(struct octeon_i2c *i2c, int target,
u8 *data, int length)
{
int i, result;
u8 tmp;
if (length < 1)
return -EINVAL;
result = octeon_i2c_start(i2c);
if (result)
return result;
octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_DATA, (target<<1) | 1);
octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL, TWSI_CTL_ENAB);
result = octeon_i2c_wait(i2c);
if (result)
return result;
for (i = 0; i < length; i++) {
tmp = octeon_i2c_read_sw(i2c, SW_TWSI_EOP_TWSI_STAT);
if ((tmp != STAT_RXDATA_ACK) && (tmp != STAT_RXADDR_ACK)) {
dev_err(i2c->dev,
"%s: bad status before read (0x%x)\n",
__func__, tmp);
return -EIO;
}
if (i+1 < length)
octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL,
TWSI_CTL_ENAB | TWSI_CTL_AAK);
else
octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL,
TWSI_CTL_ENAB);
result = octeon_i2c_wait(i2c);
if (result)
return result;
data[i] = octeon_i2c_read_sw(i2c, SW_TWSI_EOP_TWSI_DATA);
}
return 0;
}
/**
* octeon_i2c_xfer - The driver's master_xfer function.
* @adap: Pointer to the i2c_adapter structure.
* @msgs: Pointer to the messages to be processed.
* @num: Length of the MSGS array.
*
* Returns the number of messages processed, or a negative errno on
* failure.
*/
static int octeon_i2c_xfer(struct i2c_adapter *adap,
struct i2c_msg *msgs,
int num)
{
struct i2c_msg *pmsg;
int i;
int ret = 0;
struct octeon_i2c *i2c = i2c_get_adapdata(adap);
for (i = 0; ret == 0 && i < num; i++) {
pmsg = &msgs[i];
dev_dbg(i2c->dev,
"Doing %s %d byte(s) to/from 0x%02x - %d of %d messages\n",
pmsg->flags & I2C_M_RD ? "read" : "write",
pmsg->len, pmsg->addr, i + 1, num);
if (pmsg->flags & I2C_M_RD)
ret = octeon_i2c_read(i2c, pmsg->addr, pmsg->buf,
pmsg->len);
else
ret = octeon_i2c_write(i2c, pmsg->addr, pmsg->buf,
pmsg->len);
}
octeon_i2c_stop(i2c);
return (ret != 0) ? ret : num;
}
static u32 octeon_i2c_functionality(struct i2c_adapter *adap)
{
return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
}
static const struct i2c_algorithm octeon_i2c_algo = {
.master_xfer = octeon_i2c_xfer,
.functionality = octeon_i2c_functionality,
};
static struct i2c_adapter octeon_i2c_ops = {
.owner = THIS_MODULE,
.name = "OCTEON adapter",
.algo = &octeon_i2c_algo,
.timeout = 2,
};
/**
* octeon_i2c_setclock - Calculate and set clock divisors.
*/
static int __devinit octeon_i2c_setclock(struct octeon_i2c *i2c)
{
int tclk, thp_base, inc, thp_idx, mdiv_idx, ndiv_idx, foscl, diff;
int thp = 0x18, mdiv = 2, ndiv = 0, delta_hz = 1000000;
for (ndiv_idx = 0; ndiv_idx < 8 && delta_hz != 0; ndiv_idx++) {
/*
* An mdiv value of less than 2 seems to not work well
* with ds1337 RTCs, so we constrain it to larger
* values.
*/
for (mdiv_idx = 15; mdiv_idx >= 2 && delta_hz != 0; mdiv_idx--) {
/*
* For given ndiv and mdiv values check the
* two closest thp values.
*/
tclk = i2c->twsi_freq * (mdiv_idx + 1) * 10;
tclk *= (1 << ndiv_idx);
thp_base = (i2c->sys_freq / (tclk * 2)) - 1;
for (inc = 0; inc <= 1; inc++) {
thp_idx = thp_base + inc;
if (thp_idx < 5 || thp_idx > 0xff)
continue;
foscl = i2c->sys_freq / (2 * (thp_idx + 1));
foscl = foscl / (1 << ndiv_idx);
foscl = foscl / (mdiv_idx + 1) / 10;
diff = abs(foscl - i2c->twsi_freq);
if (diff < delta_hz) {
delta_hz = diff;
thp = thp_idx;
mdiv = mdiv_idx;
ndiv = ndiv_idx;
}
}
}
}
octeon_i2c_write_sw(i2c, SW_TWSI_OP_TWSI_CLK, thp);
octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CLKCTL, (mdiv << 3) | ndiv);
return 0;
}
static int __devinit octeon_i2c_initlowlevel(struct octeon_i2c *i2c)
{
u8 status;
int tries;
/* disable high level controller, enable bus access */
octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL, TWSI_CTL_ENAB);
/* reset controller */
octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_RST, 0);
for (tries = 10; tries; tries--) {
udelay(1);
status = octeon_i2c_read_sw(i2c, SW_TWSI_EOP_TWSI_STAT);
if (status == STAT_IDLE)
return 0;
}
dev_err(i2c->dev, "%s: TWSI_RST failed! (0x%x)\n", __func__, status);
return -EIO;
}
static int __devinit octeon_i2c_probe(struct platform_device *pdev)
{
int irq, result = 0;
struct octeon_i2c *i2c;
struct octeon_i2c_data *i2c_data;
struct resource *res_mem;
/* All adaptors have an irq. */
irq = platform_get_irq(pdev, 0);
if (irq < 0)
return irq;
i2c = kzalloc(sizeof(*i2c), GFP_KERNEL);
if (!i2c) {
dev_err(&pdev->dev, "kzalloc failed\n");
result = -ENOMEM;
goto out;
}
i2c->dev = &pdev->dev;
i2c_data = pdev->dev.platform_data;
res_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (res_mem == NULL) {
dev_err(i2c->dev, "found no memory resource\n");
result = -ENXIO;
goto fail_region;
}
if (i2c_data == NULL) {
dev_err(i2c->dev, "no I2C frequency data\n");
result = -ENXIO;
goto fail_region;
}
i2c->twsi_phys = res_mem->start;
i2c->regsize = resource_size(res_mem);
i2c->twsi_freq = i2c_data->i2c_freq;
i2c->sys_freq = i2c_data->sys_freq;
if (!request_mem_region(i2c->twsi_phys, i2c->regsize, res_mem->name)) {
dev_err(i2c->dev, "request_mem_region failed\n");
goto fail_region;
}
i2c->twsi_base = ioremap(i2c->twsi_phys, i2c->regsize);
init_waitqueue_head(&i2c->queue);
i2c->irq = irq;
result = request_irq(i2c->irq, octeon_i2c_isr, 0, DRV_NAME, i2c);
if (result < 0) {
dev_err(i2c->dev, "failed to attach interrupt\n");
goto fail_irq;
}
result = octeon_i2c_initlowlevel(i2c);
if (result) {
dev_err(i2c->dev, "init low level failed\n");
goto fail_add;
}
result = octeon_i2c_setclock(i2c);
if (result) {
dev_err(i2c->dev, "clock init failed\n");
goto fail_add;
}
i2c->adap = octeon_i2c_ops;
i2c->adap.dev.parent = &pdev->dev;
i2c->adap.nr = pdev->id >= 0 ? pdev->id : 0;
i2c_set_adapdata(&i2c->adap, i2c);
platform_set_drvdata(pdev, i2c);
result = i2c_add_numbered_adapter(&i2c->adap);
if (result < 0) {
dev_err(i2c->dev, "failed to add adapter\n");
goto fail_add;
}
dev_info(i2c->dev, "version %s\n", DRV_VERSION);
return result;
fail_add:
platform_set_drvdata(pdev, NULL);
free_irq(i2c->irq, i2c);
fail_irq:
iounmap(i2c->twsi_base);
release_mem_region(i2c->twsi_phys, i2c->regsize);
fail_region:
kfree(i2c);
out:
return result;
};
static int __devexit octeon_i2c_remove(struct platform_device *pdev)
{
struct octeon_i2c *i2c = platform_get_drvdata(pdev);
i2c_del_adapter(&i2c->adap);
platform_set_drvdata(pdev, NULL);
free_irq(i2c->irq, i2c);
iounmap(i2c->twsi_base);
release_mem_region(i2c->twsi_phys, i2c->regsize);
kfree(i2c);
return 0;
};
static struct platform_driver octeon_i2c_driver = {
.probe = octeon_i2c_probe,
.remove = __devexit_p(octeon_i2c_remove),
.driver = {
.owner = THIS_MODULE,
.name = DRV_NAME,
},
};
static int __init octeon_i2c_init(void)
{
int rv;
rv = platform_driver_register(&octeon_i2c_driver);
return rv;
}
static void __exit octeon_i2c_exit(void)
{
platform_driver_unregister(&octeon_i2c_driver);
}
MODULE_AUTHOR("Michael Lawnick <michael.lawnick.ext@nsn.com>");
MODULE_DESCRIPTION("I2C-Bus adapter for Cavium OCTEON processors");
MODULE_LICENSE("GPL");
MODULE_VERSION(DRV_VERSION);
MODULE_ALIAS("platform:" DRV_NAME);
module_init(octeon_i2c_init);
module_exit(octeon_i2c_exit);
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