[PATCH] i2c: pxa: enable high speed mode for i2c bus

[PATCH] i2c: pxa: enable high speed mode for i2c bus

[Leilei Shang]

To enter high speed mode, following steps should be done:
1. When running in high speed mode, i2c clock rate is different
from standard mode. Clock rate must be set according to
specification first.
2. When i2c controller sends a master code and wins arbitration,
high speed mode is entered.

If you want to enable high speed mode, the following members of
platform data should be set to proper value:
1. "high_mode" should be set to "1".
2. "master_code" should be set to "8'b 0000_1xxx"(x is 0 or 1).
   If no master_code is set, set to default value 0xe.
3. "rate" should be set according to specification.

Signed-off-by: Leilei Shang <shangll-eYqpPyKDWXRBDgjK7y7TUQ@public.gmane.org>
---
 drivers/i2c/busses/i2c-pxa.c |   64 +++++++++++++++++++++++++++++++++++++++++-
 include/linux/i2c/pxa-i2c.h  |    3 ++
 2 files changed, 66 insertions(+), 1 deletions(-)

diff --git a/drivers/i2c/busses/i2c-pxa.c b/drivers/i2c/busses/i2c-pxa.c
index ea6d45d..164324c 100644
--- a/drivers/i2c/busses/i2c-pxa.c
+++ b/drivers/i2c/busses/i2c-pxa.c
@@ -110,6 +110,8 @@ MODULE_DEVICE_TABLE(platform, i2c_pxa_id_table);
 #define ICR_SADIE	(1 << 13)	   /* slave address detected int enable */
 #define ICR_UR		(1 << 14)	   /* unit reset */
 #define ICR_FM		(1 << 15)	   /* fast mode */
+#define ICR_HS		(1 << 16)	   /* High Speed mode */
+#define ICR_GPIOEN	(1 << 19)	   /* enable GPIO mode for SCL in HS */
 
 #define ISR_RWM		(1 << 0)	   /* read/write mode */
 #define ISR_ACKNAK	(1 << 1)	   /* ack/nak status */
@@ -155,6 +157,10 @@ struct pxa_i2c {
 	int			irq;
 	unsigned int		use_pio :1;
 	unsigned int		fast_mode :1;
+	unsigned int		high_mode:1;
+	unsigned char		master_code;
+	unsigned long		rate;
+	bool			highmode_enter;
 };
 
 #define _IBMR(i2c)	((i2c)->reg_ibmr)
@@ -459,6 +465,7 @@ static void i2c_pxa_reset(struct pxa_i2c *i2c)
 
 	/* set control register values */
 	writel(I2C_ICR_INIT | (i2c->fast_mode ? ICR_FM : 0), _ICR(i2c));
+	writel(readl(_ICR(i2c)) | (i2c->high_mode ? ICR_HS : 0), _ICR(i2c));
 
 #ifdef CONFIG_I2C_PXA_SLAVE
 	dev_info(&i2c->adap.dev, "Enabling slave mode\n");
@@ -680,6 +687,34 @@ static int i2c_pxa_pio_set_master(struct pxa_i2c *i2c)
 	return 0;
 }
 
+/*
+ * PXA I2C send master code
+ * 1. Load master code to IDBR and send it.
+ *    Note for HS mode, set ICR [GPIOEN].
+ * 2. Wait until win arbitration.
+ */
+static int i2c_pxa_send_mastercode(struct pxa_i2c *i2c)
+{
+	u32 icr;
+	long timeout;
+
+	spin_lock_irq(&i2c->lock);
+	i2c->highmode_enter = true;
+	writel(i2c->master_code, _IDBR(i2c));
+
+	icr = readl(_ICR(i2c)) & ~(ICR_STOP | ICR_ALDIE);
+	icr |= ICR_GPIOEN | ICR_START | ICR_TB | ICR_ITEIE;
+	writel(icr, _ICR(i2c));
+
+	spin_unlock_irq(&i2c->lock);
+	timeout = wait_event_timeout(i2c->wait,
+			i2c->highmode_enter == false, HZ * 1);
+
+	i2c->highmode_enter = false;
+
+	return (timeout == 0) ? I2C_RETRY : 0;
+}
+
 static int i2c_pxa_do_pio_xfer(struct pxa_i2c *i2c,
 			       struct i2c_msg *msg, int num)
 {
@@ -743,6 +778,14 @@ static int i2c_pxa_do_xfer(struct pxa_i2c *i2c, struct i2c_msg *msg, int num)
 		goto out;
 	}
 
+	if (i2c->high_mode) {
+		ret = i2c_pxa_send_mastercode(i2c);
+		if (ret) {
+			dev_err(&i2c->adap.dev, "i2c_pxa_send_mastercode timeout\n");
+			goto out;
+			}
+	}
+
 	spin_lock_irq(&i2c->lock);
 
 	i2c->msg = msg;
@@ -990,11 +1033,14 @@ static irqreturn_t i2c_pxa_handler(int this_irq, void *dev_id)
 			i2c_pxa_slave_txempty(i2c, isr);
 		if (isr & ISR_IRF)
 			i2c_pxa_slave_rxfull(i2c, isr);
-	} else if (i2c->msg) {
+	} else if (i2c->msg && (!i2c->highmode_enter)) {
 		if (isr & ISR_ITE)
 			i2c_pxa_irq_txempty(i2c, isr);
 		if (isr & ISR_IRF)
 			i2c_pxa_irq_rxfull(i2c, isr);
+	} else if ((isr & ISR_ITE) && i2c->highmode_enter) {
+		i2c->highmode_enter = false;
+		wake_up(&i2c->wait);
 	} else {
 		i2c_pxa_scream_blue_murder(i2c, "spurious irq");
 	}
@@ -1079,6 +1125,11 @@ static int i2c_pxa_probe_pdata(struct platform_device *pdev,
 	if (plat) {
 		i2c->use_pio = plat->use_pio;
 		i2c->fast_mode = plat->fast_mode;
+		i2c->high_mode = plat->high_mode;
+		i2c->master_code = plat->master_code;
+		if (!i2c->master_code)
+			i2c->master_code = 0xe;
+		i2c->rate = plat->rate;
 	}
 	return 0;
 }
@@ -1151,6 +1202,7 @@ static int i2c_pxa_probe(struct platform_device *dev)
 	i2c->irq = irq;
 
 	i2c->slave_addr = I2C_PXA_SLAVE_ADDR;
+	i2c->highmode_enter = false;
 
 	if (plat) {
 #ifdef CONFIG_I2C_PXA_SLAVE
@@ -1160,6 +1212,16 @@ static int i2c_pxa_probe(struct platform_device *dev)
 		i2c->adap.class = plat->class;
 	}
 
+	if (i2c->high_mode) {
+		if (i2c->rate) {
+			clk_set_rate(i2c->clk, i2c->rate);
+			pr_info("i2c: <%s> set rate to %ld\n",
+				i2c->adap.name, clk_get_rate(i2c->clk));
+		} else
+			pr_warn("i2c: <%s> clock rate not set\n",
+				i2c->adap.name);
+	}
+
 	clk_enable(i2c->clk);
 
 	if (i2c->use_pio) {
diff --git a/include/linux/i2c/pxa-i2c.h b/include/linux/i2c/pxa-i2c.h
index 1a9f65e..53aab24 100644
--- a/include/linux/i2c/pxa-i2c.h
+++ b/include/linux/i2c/pxa-i2c.h
@@ -67,6 +67,9 @@ struct i2c_pxa_platform_data {
 	unsigned int		class;
 	unsigned int		use_pio :1;
 	unsigned int		fast_mode :1;
+	unsigned int		high_mode:1;
+	unsigned char		master_code;
+	unsigned long		rate;
 };
 
 extern void pxa_set_i2c_info(struct i2c_pxa_platform_data *info);
-- 
1.7.4.1

Re: [PATCH] i2c: pxa: enable high speed mode for i2c bus

[Wolfram Sang]

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Hi,

On Fri, Jun 07, 2013 at 02:38:17PM +0800, Leilei Shang wrote:
> To enter high speed mode, following steps should be done:
> 1. When running in high speed mode, i2c clock rate is different
> from standard mode. Clock rate must be set according to
> specification first.
> 2. When i2c controller sends a master code and wins arbitration,
> high speed mode is entered.
> 
> If you want to enable high speed mode, the following members of
> platform data should be set to proper value:

I couldn't find any support for hs-mode in pxa2xx and pxa3xx. So it
shouldn't be set in platform data, but depending on checks if this is
supported on this device at all. And why don't simply switch to it if
rate is bigger than what is supported without hs-mode?

> 1. "high_mode" should be set to "1".
> 2. "master_code" should be set to "8'b 0000_1xxx"(x is 0 or 1).
>    If no master_code is set, set to default value 0xe.
> 3. "rate" should be set according to specification.

Note that you should fall back to full-speed mode after sending the stop
bit in high-speed mode. I can't find this in the code?

> 
> Signed-off-by: Leilei Shang <shangll-eYqpPyKDWXRBDgjK7y7TUQ@public.gmane.org>

Which SoC supports this? I'd like to have a look at the datasheet.

Thanks,

   Wolfram


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Re: [PATCH] i2c: pxa: enable high speed mode for i2c bus

[James Lebron]

Hi Wolfram

    Have you finished reading datasheet?

2013/6/15 Wolfram Sang <wsa-z923LK4zBo2bacvFa/9K2g@public.gmane.org>:
> Hi,
>
> On Fri, Jun 07, 2013 at 02:38:17PM +0800, Leilei Shang wrote:
>> To enter high speed mode, following steps should be done:
>> 1. When running in high speed mode, i2c clock rate is different
>> from standard mode. Clock rate must be set according to
>> specification first.
>> 2. When i2c controller sends a master code and wins arbitration,
>> high speed mode is entered.
>>
>> If you want to enable high speed mode, the following members of
>> platform data should be set to proper value:
>
> I couldn't find any support for hs-mode in pxa2xx and pxa3xx. So it
> shouldn't be set in platform data, but depending on checks if this is
> supported on this device at all. And why don't simply switch to it if
> rate is bigger than what is supported without hs-mode?
>

1. High speed mode is hardware feature, you can't read it from
software. It's similar to fast mode, and fast mode is set in platform
data.

    The only method I can think of is to add a platform, like pxa910.
And if you enable hs mode and platform is not pxa910, we'll set it to
normal mode. Is this OK?

2. About hs mode clock setting. We don't know whether currently hs
mode clock will be changed in future. Do you think below code is OK?

if (i2c->rate)
            clk_set_rate(i2c->clk, i2c->rate);
else
            clk_set_rate(i2c->clk, 62400000);

            pr_info("i2c: <%s> set rate to %ld\n",
                i2c->adap.name, clk_get_rate(i2c->clk));

>> 1. "high_mode" should be set to "1".
>> 2. "master_code" should be set to "8'b 0000_1xxx"(x is 0 or 1).
>>    If no master_code is set, set to default value 0xe.
>> 3. "rate" should be set according to specification.
>
> Note that you should fall back to full-speed mode after sending the stop
> bit in high-speed mode. I can't find this in the code?
>

3. Will fall back to normal mode when stop bit is sent.

>>
>> Signed-off-by: Leilei Shang <shangll-eYqpPyKDWXRBDgjK7y7TUQ@public.gmane.org>
>
> Which SoC supports this? I'd like to have a look at the datasheet.
>
> Thanks,
>
>    Wolfram
>

Hope you can reply soon!

Best regards
Leilei

Re: [PATCH] i2c: pxa: enable high speed mode for i2c bus

[James Lebron]

Hi guys,

        Any comments?

2013/7/2 James Lebron <leileishangchina-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>:
> Hi Wolfram
>
>     Have you finished reading datasheet?
>
> 2013/6/15 Wolfram Sang <wsa-z923LK4zBo2bacvFa/9K2g@public.gmane.org>:
>> Hi,
>>
>> On Fri, Jun 07, 2013 at 02:38:17PM +0800, Leilei Shang wrote:
>>> To enter high speed mode, following steps should be done:
>>> 1. When running in high speed mode, i2c clock rate is different
>>> from standard mode. Clock rate must be set according to
>>> specification first.
>>> 2. When i2c controller sends a master code and wins arbitration,
>>> high speed mode is entered.
>>>
>>> If you want to enable high speed mode, the following members of
>>> platform data should be set to proper value:
>>
>> I couldn't find any support for hs-mode in pxa2xx and pxa3xx. So it
>> shouldn't be set in platform data, but depending on checks if this is
>> supported on this device at all. And why don't simply switch to it if
>> rate is bigger than what is supported without hs-mode?
>>
>
> 1. High speed mode is hardware feature, you can't read it from
> software. It's similar to fast mode, and fast mode is set in platform
> data.
>
>     The only method I can think of is to add a platform, like pxa910.
> And if you enable hs mode and platform is not pxa910, we'll set it to
> normal mode. Is this OK?
>
> 2. About hs mode clock setting. We don't know whether currently hs
> mode clock will be changed in future. Do you think below code is OK?
>
> if (i2c->rate)
>             clk_set_rate(i2c->clk, i2c->rate);
> else
>             clk_set_rate(i2c->clk, 62400000);
>
>             pr_info("i2c: <%s> set rate to %ld\n",
>                 i2c->adap.name, clk_get_rate(i2c->clk));
>
>>> 1. "high_mode" should be set to "1".
>>> 2. "master_code" should be set to "8'b 0000_1xxx"(x is 0 or 1).
>>>    If no master_code is set, set to default value 0xe.
>>> 3. "rate" should be set according to specification.
>>
>> Note that you should fall back to full-speed mode after sending the stop
>> bit in high-speed mode. I can't find this in the code?
>>
>
> 3. Will fall back to normal mode when stop bit is sent.
>
>>>
>>> Signed-off-by: Leilei Shang <shangll-eYqpPyKDWXRBDgjK7y7TUQ@public.gmane.org>
>>
>> Which SoC supports this? I'd like to have a look at the datasheet.
>>
>> Thanks,
>>
>>    Wolfram
>>
>
> Hope you can reply soon!
>
> Best regards
> Leilei

Re: [PATCH] i2c: pxa: enable high speed mode for i2c bus

[James Lebron]

Hi all

      I am still waiting for your response.....

2013/7/5 James Lebron <leileishangchina-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>:
> Hi guys,
>
>         Any comments?
>
> 2013/7/2 James Lebron <leileishangchina-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>:
>> Hi Wolfram
>>
>>     Have you finished reading datasheet?
>>
>> 2013/6/15 Wolfram Sang <wsa-z923LK4zBo2bacvFa/9K2g@public.gmane.org>:
>>> Hi,
>>>
>>> On Fri, Jun 07, 2013 at 02:38:17PM +0800, Leilei Shang wrote:
>>>> To enter high speed mode, following steps should be done:
>>>> 1. When running in high speed mode, i2c clock rate is different
>>>> from standard mode. Clock rate must be set according to
>>>> specification first.
>>>> 2. When i2c controller sends a master code and wins arbitration,
>>>> high speed mode is entered.
>>>>
>>>> If you want to enable high speed mode, the following members of
>>>> platform data should be set to proper value:
>>>
>>> I couldn't find any support for hs-mode in pxa2xx and pxa3xx. So it
>>> shouldn't be set in platform data, but depending on checks if this is
>>> supported on this device at all. And why don't simply switch to it if
>>> rate is bigger than what is supported without hs-mode?
>>>
>>
>> 1. High speed mode is hardware feature, you can't read it from
>> software. It's similar to fast mode, and fast mode is set in platform
>> data.
>>
>>     The only method I can think of is to add a platform, like pxa910.
>> And if you enable hs mode and platform is not pxa910, we'll set it to
>> normal mode. Is this OK?
>>
>> 2. About hs mode clock setting. We don't know whether currently hs
>> mode clock will be changed in future. Do you think below code is OK?
>>
>> if (i2c->rate)
>>             clk_set_rate(i2c->clk, i2c->rate);
>> else
>>             clk_set_rate(i2c->clk, 62400000);
>>
>>             pr_info("i2c: <%s> set rate to %ld\n",
>>                 i2c->adap.name, clk_get_rate(i2c->clk));
>>
>>>> 1. "high_mode" should be set to "1".
>>>> 2. "master_code" should be set to "8'b 0000_1xxx"(x is 0 or 1).
>>>>    If no master_code is set, set to default value 0xe.
>>>> 3. "rate" should be set according to specification.
>>>
>>> Note that you should fall back to full-speed mode after sending the stop
>>> bit in high-speed mode. I can't find this in the code?
>>>
>>
>> 3. Will fall back to normal mode when stop bit is sent.
>>
>>>>
>>>> Signed-off-by: Leilei Shang <shangll-eYqpPyKDWXRBDgjK7y7TUQ@public.gmane.org>
>>>
>>> Which SoC supports this? I'd like to have a look at the datasheet.
>>>
>>> Thanks,
>>>
>>>    Wolfram
>>>
>>
>> Hope you can reply soon!
>>
>> Best regards
>> Leilei

Re: [PATCH] i2c: pxa: enable high speed mode for i2c bus

[James Lebron]

Hi Guys

      Any comments?

2013/7/11 James Lebron <leileishangchina-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>:
> Hi all
>
>       I am still waiting for your response.....
>
> 2013/7/5 James Lebron <leileishangchina-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>:
>> Hi guys,
>>
>>         Any comments?
>>
>> 2013/7/2 James Lebron <leileishangchina-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>:
>>> Hi Wolfram
>>>
>>>     Have you finished reading datasheet?
>>>
>>> 2013/6/15 Wolfram Sang <wsa-z923LK4zBo2bacvFa/9K2g@public.gmane.org>:
>>>> Hi,
>>>>
>>>> On Fri, Jun 07, 2013 at 02:38:17PM +0800, Leilei Shang wrote:
>>>>> To enter high speed mode, following steps should be done:
>>>>> 1. When running in high speed mode, i2c clock rate is different
>>>>> from standard mode. Clock rate must be set according to
>>>>> specification first.
>>>>> 2. When i2c controller sends a master code and wins arbitration,
>>>>> high speed mode is entered.
>>>>>
>>>>> If you want to enable high speed mode, the following members of
>>>>> platform data should be set to proper value:
>>>>
>>>> I couldn't find any support for hs-mode in pxa2xx and pxa3xx. So it
>>>> shouldn't be set in platform data, but depending on checks if this is
>>>> supported on this device at all. And why don't simply switch to it if
>>>> rate is bigger than what is supported without hs-mode?
>>>>
>>>
>>> 1. High speed mode is hardware feature, you can't read it from
>>> software. It's similar to fast mode, and fast mode is set in platform
>>> data.
>>>
>>>     The only method I can think of is to add a platform, like pxa910.
>>> And if you enable hs mode and platform is not pxa910, we'll set it to
>>> normal mode. Is this OK?
>>>
>>> 2. About hs mode clock setting. We don't know whether currently hs
>>> mode clock will be changed in future. Do you think below code is OK?
>>>
>>> if (i2c->rate)
>>>             clk_set_rate(i2c->clk, i2c->rate);
>>> else
>>>             clk_set_rate(i2c->clk, 62400000);
>>>
>>>             pr_info("i2c: <%s> set rate to %ld\n",
>>>                 i2c->adap.name, clk_get_rate(i2c->clk));
>>>
>>>>> 1. "high_mode" should be set to "1".
>>>>> 2. "master_code" should be set to "8'b 0000_1xxx"(x is 0 or 1).
>>>>>    If no master_code is set, set to default value 0xe.
>>>>> 3. "rate" should be set according to specification.
>>>>
>>>> Note that you should fall back to full-speed mode after sending the stop
>>>> bit in high-speed mode. I can't find this in the code?
>>>>
>>>
>>> 3. Will fall back to normal mode when stop bit is sent.
>>>
>>>>>
>>>>> Signed-off-by: Leilei Shang <shangll-eYqpPyKDWXRBDgjK7y7TUQ@public.gmane.org>
>>>>
>>>> Which SoC supports this? I'd like to have a look at the datasheet.
>>>>
>>>> Thanks,
>>>>
>>>>    Wolfram
>>>>
>>>
>>> Hope you can reply soon!
>>>
>>> Best regards
>>> Leilei

Re: [PATCH] i2c: pxa: enable high speed mode for i2c bus

[James Lebron]

Hi All

Would you please help to look at this patch?

Thanks!

2013/7/22 James Lebron <leileishangchina-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>:
> Hi Guys
>
>       Any comments?
>
> 2013/7/11 James Lebron <leileishangchina-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>:
>> Hi all
>>
>>       I am still waiting for your response.....
>>
>> 2013/7/5 James Lebron <leileishangchina-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>:
>>> Hi guys,
>>>
>>>         Any comments?
>>>
>>> 2013/7/2 James Lebron <leileishangchina-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>:
>>>> Hi Wolfram
>>>>
>>>>     Have you finished reading datasheet?
>>>>
>>>> 2013/6/15 Wolfram Sang <wsa-z923LK4zBo2bacvFa/9K2g@public.gmane.org>:
>>>>> Hi,
>>>>>
>>>>> On Fri, Jun 07, 2013 at 02:38:17PM +0800, Leilei Shang wrote:
>>>>>> To enter high speed mode, following steps should be done:
>>>>>> 1. When running in high speed mode, i2c clock rate is different
>>>>>> from standard mode. Clock rate must be set according to
>>>>>> specification first.
>>>>>> 2. When i2c controller sends a master code and wins arbitration,
>>>>>> high speed mode is entered.
>>>>>>
>>>>>> If you want to enable high speed mode, the following members of
>>>>>> platform data should be set to proper value:
>>>>>
>>>>> I couldn't find any support for hs-mode in pxa2xx and pxa3xx. So it
>>>>> shouldn't be set in platform data, but depending on checks if this is
>>>>> supported on this device at all. And why don't simply switch to it if
>>>>> rate is bigger than what is supported without hs-mode?
>>>>>
>>>>
>>>> 1. High speed mode is hardware feature, you can't read it from
>>>> software. It's similar to fast mode, and fast mode is set in platform
>>>> data.
>>>>
>>>>     The only method I can think of is to add a platform, like pxa910.
>>>> And if you enable hs mode and platform is not pxa910, we'll set it to
>>>> normal mode. Is this OK?
>>>>
>>>> 2. About hs mode clock setting. We don't know whether currently hs
>>>> mode clock will be changed in future. Do you think below code is OK?
>>>>
>>>> if (i2c->rate)
>>>>             clk_set_rate(i2c->clk, i2c->rate);
>>>> else
>>>>             clk_set_rate(i2c->clk, 62400000);
>>>>
>>>>             pr_info("i2c: <%s> set rate to %ld\n",
>>>>                 i2c->adap.name, clk_get_rate(i2c->clk));
>>>>
>>>>>> 1. "high_mode" should be set to "1".
>>>>>> 2. "master_code" should be set to "8'b 0000_1xxx"(x is 0 or 1).
>>>>>>    If no master_code is set, set to default value 0xe.
>>>>>> 3. "rate" should be set according to specification.
>>>>>
>>>>> Note that you should fall back to full-speed mode after sending the stop
>>>>> bit in high-speed mode. I can't find this in the code?
>>>>>
>>>>
>>>> 3. Will fall back to normal mode when stop bit is sent.
>>>>
>>>>>>
>>>>>> Signed-off-by: Leilei Shang <shangll-eYqpPyKDWXRBDgjK7y7TUQ@public.gmane.org>
>>>>>
>>>>> Which SoC supports this? I'd like to have a look at the datasheet.
>>>>>
>>>>> Thanks,
>>>>>
>>>>>    Wolfram
>>>>>
>>>>
>>>> Hope you can reply soon!
>>>>
>>>> Best regards
>>>> Leilei

Re: [PATCH] i2c: pxa: enable high speed mode for i2c bus

[James Lebron]

Hi

Would you please take a tiny time to look at this?

2013/7/30 James Lebron <leileishangchina-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>:
> Hi All
>
> Would you please help to look at this patch?
>
> Thanks!
>
> 2013/7/22 James Lebron <leileishangchina-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>:
>> Hi Guys
>>
>>       Any comments?
>>
>> 2013/7/11 James Lebron <leileishangchina-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>:
>>> Hi all
>>>
>>>       I am still waiting for your response.....
>>>
>>> 2013/7/5 James Lebron <leileishangchina-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>:
>>>> Hi guys,
>>>>
>>>>         Any comments?
>>>>
>>>> 2013/7/2 James Lebron <leileishangchina-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>:
>>>>> Hi Wolfram
>>>>>
>>>>>     Have you finished reading datasheet?
>>>>>
>>>>> 2013/6/15 Wolfram Sang <wsa-z923LK4zBo2bacvFa/9K2g@public.gmane.org>:
>>>>>> Hi,
>>>>>>
>>>>>> On Fri, Jun 07, 2013 at 02:38:17PM +0800, Leilei Shang wrote:
>>>>>>> To enter high speed mode, following steps should be done:
>>>>>>> 1. When running in high speed mode, i2c clock rate is different
>>>>>>> from standard mode. Clock rate must be set according to
>>>>>>> specification first.
>>>>>>> 2. When i2c controller sends a master code and wins arbitration,
>>>>>>> high speed mode is entered.
>>>>>>>
>>>>>>> If you want to enable high speed mode, the following members of
>>>>>>> platform data should be set to proper value:
>>>>>>
>>>>>> I couldn't find any support for hs-mode in pxa2xx and pxa3xx. So it
>>>>>> shouldn't be set in platform data, but depending on checks if this is
>>>>>> supported on this device at all. And why don't simply switch to it if
>>>>>> rate is bigger than what is supported without hs-mode?
>>>>>>
>>>>>
>>>>> 1. High speed mode is hardware feature, you can't read it from
>>>>> software. It's similar to fast mode, and fast mode is set in platform
>>>>> data.
>>>>>
>>>>>     The only method I can think of is to add a platform, like pxa910.
>>>>> And if you enable hs mode and platform is not pxa910, we'll set it to
>>>>> normal mode. Is this OK?
>>>>>
>>>>> 2. About hs mode clock setting. We don't know whether currently hs
>>>>> mode clock will be changed in future. Do you think below code is OK?
>>>>>
>>>>> if (i2c->rate)
>>>>>             clk_set_rate(i2c->clk, i2c->rate);
>>>>> else
>>>>>             clk_set_rate(i2c->clk, 62400000);
>>>>>
>>>>>             pr_info("i2c: <%s> set rate to %ld\n",
>>>>>                 i2c->adap.name, clk_get_rate(i2c->clk));
>>>>>
>>>>>>> 1. "high_mode" should be set to "1".
>>>>>>> 2. "master_code" should be set to "8'b 0000_1xxx"(x is 0 or 1).
>>>>>>>    If no master_code is set, set to default value 0xe.
>>>>>>> 3. "rate" should be set according to specification.
>>>>>>
>>>>>> Note that you should fall back to full-speed mode after sending the stop
>>>>>> bit in high-speed mode. I can't find this in the code?
>>>>>>
>>>>>
>>>>> 3. Will fall back to normal mode when stop bit is sent.
>>>>>
>>>>>>>
>>>>>>> Signed-off-by: Leilei Shang <shangll-eYqpPyKDWXRBDgjK7y7TUQ@public.gmane.org>
>>>>>>
>>>>>> Which SoC supports this? I'd like to have a look at the datasheet.
>>>>>>
>>>>>> Thanks,
>>>>>>
>>>>>>    Wolfram
>>>>>>
>>>>>
>>>>> Hope you can reply soon!
>>>>>
>>>>> Best regards
>>>>> Leilei

Re: [PATCH] i2c: pxa: enable high speed mode for i2c bus

[Wolfram Sang]

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On Tue, Jul 02, 2013 at 10:10:29AM +0800, James Lebron wrote:
> Hi Wolfram
> 
>     Have you finished reading datasheet?

Sadly not. I couldn't find the reference manual freely available. That
was a problem when reviewing this patch.

> 1. High speed mode is hardware feature, you can't read it from
> software. It's similar to fast mode, and fast mode is set in platform
> data.

Yes, setting fast mode in platform_data is troublesome, too. Better
would be to introduce a new platform_id (say, pxa910-i2c) and to deduce
from that id that only this version has high speed mode. I am accepting
the current solution since it is consistent with fast mode, but all this
needs to be fixed if pxa is going devicetree.

Thanks,

   Wolfram


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