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i2c-stu300: I2C STU300 stability updates
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- blk clk is enabled when an irq arrives. The clk should be enabled,
  but just to make sure.
- All error bits are handled no matter state machine state
- All irq's will run complete() except for irq's that wasn't an event.
- No more looking into status registers just in case an interrupt
  has happend and the irq handle wasn't executed.
- irq_disable/enable are now separete functions.
- clk settings calculation changed to round upwards instead of
  downwards.
- Number of address send attempts before giving up is increased to 12
  from 10 since it most times take 8 tries before getting through.

Signed-off-by: Linus Walleij <linus.walleij@stericsson.com>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>
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Linus Walleij authored and Ben Dooks committed Aug 20, 2009
1 parent 6114978 commit c37faaf
Showing 1 changed file with 92 additions and 65 deletions.
157 changes: 92 additions & 65 deletions drivers/i2c/busses/i2c-stu300.c
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Original file line number Diff line number Diff line change
Expand Up @@ -117,7 +117,8 @@ enum stu300_error {
STU300_ERROR_NONE = 0,
STU300_ERROR_ACKNOWLEDGE_FAILURE,
STU300_ERROR_BUS_ERROR,
STU300_ERROR_ARBITRATION_LOST
STU300_ERROR_ARBITRATION_LOST,
STU300_ERROR_UNKNOWN
};

/* timeout waiting for the controller to respond */
Expand All @@ -127,7 +128,7 @@ enum stu300_error {
* The number of address send athemps tried before giving up.
* If the first one failes it seems like 5 to 8 attempts are required.
*/
#define NUM_ADDR_RESEND_ATTEMPTS 10
#define NUM_ADDR_RESEND_ATTEMPTS 12

/* I2C clock speed, in Hz 0-400kHz*/
static unsigned int scl_frequency = 100000;
Expand All @@ -149,6 +150,7 @@ module_param(scl_frequency, uint, 0644);
* @msg_index: index of current message
* @msg_len: length of current message
*/

struct stu300_dev {
struct platform_device *pdev;
struct i2c_adapter adapter;
Expand Down Expand Up @@ -188,6 +190,27 @@ static inline u32 stu300_r8(void __iomem *address)
return readl(address) & 0x000000FFU;
}

static void stu300_irq_enable(struct stu300_dev *dev)
{
u32 val;
val = stu300_r8(dev->virtbase + I2C_CR);
val |= I2C_CR_INTERRUPT_ENABLE;
/* Twice paranoia (possible HW glitch) */
stu300_wr8(val, dev->virtbase + I2C_CR);
stu300_wr8(val, dev->virtbase + I2C_CR);
}

static void stu300_irq_disable(struct stu300_dev *dev)
{
u32 val;
val = stu300_r8(dev->virtbase + I2C_CR);
val &= ~I2C_CR_INTERRUPT_ENABLE;
/* Twice paranoia (possible HW glitch) */
stu300_wr8(val, dev->virtbase + I2C_CR);
stu300_wr8(val, dev->virtbase + I2C_CR);
}


/*
* Tells whether a certain event or events occurred in
* response to a command. The events represent states in
Expand All @@ -196,21 +219,39 @@ static inline u32 stu300_r8(void __iomem *address)
* documentation and can only be treated as abstract state
* machine states.
*
* @ret 0 = event has not occurred, any other value means
* the event occurred.
* @ret 0 = event has not occurred or unknown error, any
* other value means the correct event occurred or an error.
*/

static int stu300_event_occurred(struct stu300_dev *dev,
enum stu300_event mr_event) {
u32 status1;
u32 status2;

/* What event happened? */
status1 = stu300_r8(dev->virtbase + I2C_SR1);

if (!(status1 & I2C_SR1_EVF_IND))
/* No event at all */
return 0;

status2 = stu300_r8(dev->virtbase + I2C_SR2);

/* Block any multiple interrupts */
stu300_irq_disable(dev);

/* Check for errors first */
if (status2 & I2C_SR2_AF_IND) {
dev->cmd_err = STU300_ERROR_ACKNOWLEDGE_FAILURE;
return 1;
} else if (status2 & I2C_SR2_BERR_IND) {
dev->cmd_err = STU300_ERROR_BUS_ERROR;
return 1;
} else if (status2 & I2C_SR2_ARLO_IND) {
dev->cmd_err = STU300_ERROR_ARBITRATION_LOST;
return 1;
}

switch (mr_event) {
case STU300_EVENT_1:
if (status1 & I2C_SR1_ADSL_IND)
Expand All @@ -221,10 +262,6 @@ static int stu300_event_occurred(struct stu300_dev *dev,
case STU300_EVENT_7:
case STU300_EVENT_8:
if (status1 & I2C_SR1_BTF_IND) {
if (status2 & I2C_SR2_AF_IND)
dev->cmd_err = STU300_ERROR_ACKNOWLEDGE_FAILURE;
else if (status2 & I2C_SR2_BERR_IND)
dev->cmd_err = STU300_ERROR_BUS_ERROR;
return 1;
}
break;
Expand All @@ -240,8 +277,6 @@ static int stu300_event_occurred(struct stu300_dev *dev,
case STU300_EVENT_6:
if (status2 & I2C_SR2_ENDAD_IND) {
/* First check for any errors */
if (status2 & I2C_SR2_AF_IND)
dev->cmd_err = STU300_ERROR_ACKNOWLEDGE_FAILURE;
return 1;
}
break;
Expand All @@ -252,8 +287,15 @@ static int stu300_event_occurred(struct stu300_dev *dev,
default:
break;
}
if (status2 & I2C_SR2_ARLO_IND)
dev->cmd_err = STU300_ERROR_ARBITRATION_LOST;
/* If we get here, we're on thin ice.
* Here we are in a status where we have
* gotten a response that does not match
* what we requested.
*/
dev->cmd_err = STU300_ERROR_UNKNOWN;
dev_err(&dev->pdev->dev,
"Unhandled interrupt! %d sr1: 0x%x sr2: 0x%x\n",
mr_event, status1, status2);
return 0;
}

Expand All @@ -262,21 +304,20 @@ static irqreturn_t stu300_irh(int irq, void *data)
struct stu300_dev *dev = data;
int res;

/* Just make sure that the block is clocked */
clk_enable(dev->clk);

/* See if this was what we were waiting for */
spin_lock(&dev->cmd_issue_lock);
if (dev->cmd_event != STU300_EVENT_NONE) {
res = stu300_event_occurred(dev, dev->cmd_event);
if (res || dev->cmd_err != STU300_ERROR_NONE) {
u32 val;

complete(&dev->cmd_complete);
/* Block any multiple interrupts */
val = stu300_r8(dev->virtbase + I2C_CR);
val &= ~I2C_CR_INTERRUPT_ENABLE;
stu300_wr8(val, dev->virtbase + I2C_CR);
}
}

res = stu300_event_occurred(dev, dev->cmd_event);
if (res || dev->cmd_err != STU300_ERROR_NONE)
complete(&dev->cmd_complete);

spin_unlock(&dev->cmd_issue_lock);

clk_disable(dev->clk);

return IRQ_HANDLED;
}

Expand Down Expand Up @@ -308,7 +349,6 @@ static int stu300_start_and_await_event(struct stu300_dev *dev,
stu300_wr8(cr_value, dev->virtbase + I2C_CR);
ret = wait_for_completion_interruptible_timeout(&dev->cmd_complete,
STU300_TIMEOUT);

if (ret < 0) {
dev_err(&dev->pdev->dev,
"wait_for_completion_interruptible_timeout() "
Expand Down Expand Up @@ -342,7 +382,6 @@ static int stu300_await_event(struct stu300_dev *dev,
enum stu300_event mr_event)
{
int ret;
u32 val;

if (unlikely(irqs_disabled())) {
/* TODO: implement polling for this case if need be. */
Expand All @@ -354,36 +393,18 @@ static int stu300_await_event(struct stu300_dev *dev,
/* Is it already here? */
spin_lock_irq(&dev->cmd_issue_lock);
dev->cmd_err = STU300_ERROR_NONE;
if (stu300_event_occurred(dev, mr_event)) {
spin_unlock_irq(&dev->cmd_issue_lock);
goto exit_await_check_err;
}
init_completion(&dev->cmd_complete);
dev->cmd_err = STU300_ERROR_NONE;
dev->cmd_event = mr_event;

/* Turn on the I2C interrupt for current operation */
val = stu300_r8(dev->virtbase + I2C_CR);
val |= I2C_CR_INTERRUPT_ENABLE;
stu300_wr8(val, dev->virtbase + I2C_CR);

/* Twice paranoia (possible HW glitch) */
stu300_wr8(val, dev->virtbase + I2C_CR);
init_completion(&dev->cmd_complete);

/* Check again: is it already here? */
if (unlikely(stu300_event_occurred(dev, mr_event))) {
/* Disable IRQ again. */
val &= ~I2C_CR_INTERRUPT_ENABLE;
stu300_wr8(val, dev->virtbase + I2C_CR);
spin_unlock_irq(&dev->cmd_issue_lock);
goto exit_await_check_err;
}
/* Turn on the I2C interrupt for current operation */
stu300_irq_enable(dev);

/* Unlock the command block and wait for the event to occur */
spin_unlock_irq(&dev->cmd_issue_lock);

ret = wait_for_completion_interruptible_timeout(&dev->cmd_complete,
STU300_TIMEOUT);

if (ret < 0) {
dev_err(&dev->pdev->dev,
"wait_for_completion_interruptible_timeout()"
Expand All @@ -401,7 +422,6 @@ static int stu300_await_event(struct stu300_dev *dev,
return -ETIMEDOUT;
}

exit_await_check_err:
if (dev->cmd_err != STU300_ERROR_NONE) {
if (mr_event != STU300_EVENT_6) {
dev_err(&dev->pdev->dev, "controller "
Expand Down Expand Up @@ -457,18 +477,19 @@ struct stu300_clkset {
};

static const struct stu300_clkset stu300_clktable[] = {
{ 0, 0xFFU },
{ 2500000, I2C_OAR2_FR_25_10MHZ },
{ 10000000, I2C_OAR2_FR_10_1667MHZ },
{ 16670000, I2C_OAR2_FR_1667_2667MHZ },
{ 26670000, I2C_OAR2_FR_2667_40MHZ },
{ 40000000, I2C_OAR2_FR_40_5333MHZ },
{ 53330000, I2C_OAR2_FR_5333_66MHZ },
{ 66000000, I2C_OAR2_FR_66_80MHZ },
{ 80000000, I2C_OAR2_FR_80_100MHZ },
{ 0, 0xFFU },
{ 2500000, I2C_OAR2_FR_25_10MHZ },
{ 10000000, I2C_OAR2_FR_10_1667MHZ },
{ 16670000, I2C_OAR2_FR_1667_2667MHZ },
{ 26670000, I2C_OAR2_FR_2667_40MHZ },
{ 40000000, I2C_OAR2_FR_40_5333MHZ },
{ 53330000, I2C_OAR2_FR_5333_66MHZ },
{ 66000000, I2C_OAR2_FR_66_80MHZ },
{ 80000000, I2C_OAR2_FR_80_100MHZ },
{ 100000000, 0xFFU },
};


static int stu300_set_clk(struct stu300_dev *dev, unsigned long clkrate)
{

Expand All @@ -494,10 +515,10 @@ static int stu300_set_clk(struct stu300_dev *dev, unsigned long clkrate)

if (dev->speed > 100000)
/* Fast Mode I2C */
val = ((clkrate/dev->speed)-9)/3;
val = ((clkrate/dev->speed) - 9)/3 + 1;
else
/* Standard Mode I2C */
val = ((clkrate/dev->speed)-7)/2;
val = ((clkrate/dev->speed) - 7)/2 + 1;

/* According to spec the divider must be > 2 */
if (val < 0x002) {
Expand Down Expand Up @@ -557,6 +578,7 @@ static int stu300_init_hw(struct stu300_dev *dev)
*/
clkrate = clk_get_rate(dev->clk);
ret = stu300_set_clk(dev, clkrate);

if (ret)
return ret;
/*
Expand Down Expand Up @@ -641,7 +663,6 @@ static int stu300_xfer_msg(struct i2c_adapter *adap,
int attempts = 0;
struct stu300_dev *dev = i2c_get_adapdata(adap);


clk_enable(dev->clk);

/* Remove this if (0) to trace each and every message. */
Expand Down Expand Up @@ -715,14 +736,15 @@ static int stu300_xfer_msg(struct i2c_adapter *adap,

if (attempts < NUM_ADDR_RESEND_ATTEMPTS && attempts > 0) {
dev_dbg(&dev->pdev->dev, "managed to get address "
"through after %d attempts\n", attempts);
"through after %d attempts\n", attempts);
} else if (attempts == NUM_ADDR_RESEND_ATTEMPTS) {
dev_dbg(&dev->pdev->dev, "I give up, tried %d times "
"to resend address.\n",
NUM_ADDR_RESEND_ATTEMPTS);
"to resend address.\n",
NUM_ADDR_RESEND_ATTEMPTS);
goto exit_disable;
}


if (msg->flags & I2C_M_RD) {
/* READ: we read the actual bytes one at a time */
for (i = 0; i < msg->len; i++) {
Expand Down Expand Up @@ -804,8 +826,10 @@ static int stu300_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
{
int ret = -1;
int i;

struct stu300_dev *dev = i2c_get_adapdata(adap);
dev->msg_len = num;

for (i = 0; i < num; i++) {
/*
* Another driver appears to send stop for each message,
Expand All @@ -817,6 +841,7 @@ static int stu300_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
dev->msg_index = i;

ret = stu300_xfer_msg(adap, &msgs[i], (i == (num - 1)));

if (ret != 0) {
num = ret;
break;
Expand Down Expand Up @@ -845,6 +870,7 @@ stu300_probe(struct platform_device *pdev)
struct resource *res;
int bus_nr;
int ret = 0;
char clk_name[] = "I2C0";

dev = kzalloc(sizeof(struct stu300_dev), GFP_KERNEL);
if (!dev) {
Expand All @@ -854,7 +880,8 @@ stu300_probe(struct platform_device *pdev)
}

bus_nr = pdev->id;
dev->clk = clk_get(&pdev->dev, NULL);
clk_name[3] += (char)bus_nr;
dev->clk = clk_get(&pdev->dev, clk_name);
if (IS_ERR(dev->clk)) {
ret = PTR_ERR(dev->clk);
dev_err(&pdev->dev, "could not retrieve i2c bus clock\n");
Expand Down

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