[PATCH 0/2] powerpc: i2c-mpc: make I2C bus speed configurable

[PATCH 0/2] powerpc: i2c-mpc: make I2C bus speed configurable

[Wolfgang Grandegger]

Following (most of) Grant's suggestions to my RFC:

http://ozlabs.org/pipermail/linuxppc-dev/2009-March/069820.html

this new patch series now uses:

- the I2c node property "fsl,preserve-clocking" to overtake the
  clock settings from the boot loader. The first patch provides this
  feature and can be applied *without* delay. This rest will take
  more time and discussion, I'm afraid  :-( .

- the OF match table to define the I2C clock properties, especially
  the source clock pre-scaler:

  static const struct of_device_id mpc_i2c_of_match[] = {
	{.compatible = "fsl,mpc5200b-i2c",
	 .data = (void *)FSL_I2C_DEV_CLOCK_5200, },
	{.compatible = "fsl,mpc5200-i2c",
	 .data = (void *)FSL_I2C_DEV_CLOCK_5200, },
	{.compatible = "fsl,mpc8313-i2c",
	 .data = (void *)FSL_I2C_DEV_SEPARATE_DFSRR, },
	{.compatible = "fsl,mpc8543-i2c",
	 .data = (void *)(FSL_I2C_DEV_SEPARATE_DFSRR |
			  FSL_I2C_DEV_CLOCK_DIV2), },
	{.compatible = "fsl,mpc8544-i2c",
	 .data = (void *)(FSL_I2C_DEV_SEPARATE_DFSRR |
			  FSL_I2C_DEV_CLOCK_DIV23), },
	/* Backward compatibility */
	{.compatible = "fsl-i2c", },
	{},
  };

  The "data" field defines the relevant I2C flags.

- arch-specific tables and functions to get the proper Freqency
  Divider Register (fdr). I added them to sysdev/fsl_soc.c for
  the MPC8xxx and to platforms/52xx/mpc52xx_common.c for the
  MPC52xx. This also solves the problem with arch-specific
  functions, e.g. for getting the bus frequency.

- dev_dbg() and dev_info() to profit from a more descriptive output.

Hope this solution is OK now?

Thanks,

Wolfgang.

[PATCH 1/2] powerpc: i2c-mpc: preserve I2C clocking

[Wolfgang Grandegger]

The I2c node property "fsl,preserve-clocking" allows to overtake the
clock settings from the boot loader and avoids the hard-coded setting.

Signed-off-by: Wolfgang Grandegger <wg@grandegger.com>
---
 drivers/i2c/busses/i2c-mpc.c |   24 ++++++++++++++++--------
 1 file changed, 16 insertions(+), 8 deletions(-)

Index: linux-2.6/drivers/i2c/busses/i2c-mpc.c
===================================================================
--- linux-2.6.orig/drivers/i2c/busses/i2c-mpc.c	2009-03-31 13:25:08.000000000 +0200
+++ linux-2.6/drivers/i2c/busses/i2c-mpc.c	2009-03-31 13:28:03.000000000 +0200
@@ -318,17 +318,24 @@
 {
 	int result = 0;
 	struct mpc_i2c *i2c;
+	int set_clock;
 
 	i2c = kzalloc(sizeof(*i2c), GFP_KERNEL);
 	if (!i2c)
 		return -ENOMEM;
 
-	if (of_get_property(op->node, "dfsrr", NULL))
-		i2c->flags |= FSL_I2C_DEV_SEPARATE_DFSRR;
-
-	if (of_device_is_compatible(op->node, "fsl,mpc5200-i2c") ||
-			of_device_is_compatible(op->node, "mpc5200-i2c"))
-		i2c->flags |= FSL_I2C_DEV_CLOCK_5200;
+	if (of_get_property(op->node, "fsl,preserve-clocking", NULL)) {
+		set_clock = 0;
+	} else {
+		set_clock = 1;
+
+		if (of_get_property(op->node, "dfsrr", NULL))
+			i2c->flags |= FSL_I2C_DEV_SEPARATE_DFSRR;
+
+		if (of_device_is_compatible(op->node, "fsl,mpc5200-i2c") ||
+		    of_device_is_compatible(op->node, "mpc5200-i2c"))
+			i2c->flags |= FSL_I2C_DEV_CLOCK_5200;
+	}
 
 	init_waitqueue_head(&i2c->queue);
 
@@ -348,8 +355,9 @@
 			goto fail_request;
 		}
 	}
-	
-	mpc_i2c_setclock(i2c);
+
+	if (set_clock)
+		mpc_i2c_setclock(i2c);
 
 	dev_set_drvdata(&op->dev, i2c);
 

Re: [PATCH 1/2] powerpc: i2c-mpc: preserve I2C clocking

[Wolfram Sang]

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On Tue, Mar 31, 2009 at 02:50:29PM +0200, Wolfgang Grandegger wrote:
> The I2c node property "fsl,preserve-clocking" allows to overtake the
> clock settings from the boot loader and avoids the hard-coded setting.
> 
> Signed-off-by: Wolfgang Grandegger <wg@grandegger.com>
> ---
>  drivers/i2c/busses/i2c-mpc.c |   24 ++++++++++++++++--------
>  1 file changed, 16 insertions(+), 8 deletions(-)
> 
> Index: linux-2.6/drivers/i2c/busses/i2c-mpc.c
> ===================================================================
> --- linux-2.6.orig/drivers/i2c/busses/i2c-mpc.c	2009-03-31 13:25:08.000000000 +0200
> +++ linux-2.6/drivers/i2c/busses/i2c-mpc.c	2009-03-31 13:28:03.000000000 +0200
> @@ -318,17 +318,24 @@
>  {
>  	int result = 0;
>  	struct mpc_i2c *i2c;
> +	int set_clock;
>  
>  	i2c = kzalloc(sizeof(*i2c), GFP_KERNEL);
>  	if (!i2c)
>  		return -ENOMEM;
>  
> -	if (of_get_property(op->node, "dfsrr", NULL))
> -		i2c->flags |= FSL_I2C_DEV_SEPARATE_DFSRR;
> -
> -	if (of_device_is_compatible(op->node, "fsl,mpc5200-i2c") ||
> -			of_device_is_compatible(op->node, "mpc5200-i2c"))
> -		i2c->flags |= FSL_I2C_DEV_CLOCK_5200;
> +	if (of_get_property(op->node, "fsl,preserve-clocking", NULL)) {
> +		set_clock = 0;
> +	} else {
> +		set_clock = 1;
> +
> +		if (of_get_property(op->node, "dfsrr", NULL))
> +			i2c->flags |= FSL_I2C_DEV_SEPARATE_DFSRR;
> +
> +		if (of_device_is_compatible(op->node, "fsl,mpc5200-i2c") ||
> +		    of_device_is_compatible(op->node, "mpc5200-i2c"))
> +			i2c->flags |= FSL_I2C_DEV_CLOCK_5200;
> +	}
>  
>  	init_waitqueue_head(&i2c->queue);
>  
> @@ -348,8 +355,9 @@
>  			goto fail_request;
>  		}
>  	}
> -	
> -	mpc_i2c_setclock(i2c);
> +
> +	if (set_clock)
> +		mpc_i2c_setclock(i2c);

Can't we drop 'set_clock' with something like this here?

+	if (!of_get_property(op->node, "fsl,preserve-clocking", NULL)) {
+
+		if (of_get_property(op->node, "dfsrr", NULL))
+			i2c->flags |= FSL_I2C_DEV_SEPARATE_DFSRR;
+
+		if (of_device_is_compatible(op->node, "fsl,mpc5200-i2c") ||
+		    of_device_is_compatible(op->node, "mpc5200-i2c"))
+			i2c->flags |= FSL_I2C_DEV_CLOCK_5200;
+
+		mpc_i2c_setclock(i2c);
+	}

>  
>  	dev_set_drvdata(&op->dev, i2c);
>  
> 
> _______________________________________________
> devicetree-discuss mailing list
> devicetree-discuss@ozlabs.org
> https://ozlabs.org/mailman/listinfo/devicetree-discuss

Regards,

   Wolfram

-- 
Pengutronix e.K.                           | Wolfram Sang                |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |

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Re: [PATCH 1/2] powerpc: i2c-mpc: preserve I2C clocking

[Wolfgang Grandegger]

Wolfram Sang wrote:
> On Tue, Mar 31, 2009 at 02:50:29PM +0200, Wolfgang Grandegger wrote:
>> The I2c node property "fsl,preserve-clocking" allows to overtake the
>> clock settings from the boot loader and avoids the hard-coded setting.
>>
>> Signed-off-by: Wolfgang Grandegger <wg@grandegger.com>
>> ---
>>  drivers/i2c/busses/i2c-mpc.c |   24 ++++++++++++++++--------
>>  1 file changed, 16 insertions(+), 8 deletions(-)
>>
>> Index: linux-2.6/drivers/i2c/busses/i2c-mpc.c
>> ===================================================================
>> --- linux-2.6.orig/drivers/i2c/busses/i2c-mpc.c	2009-03-31 13:25:08.000000000 +0200
>> +++ linux-2.6/drivers/i2c/busses/i2c-mpc.c	2009-03-31 13:28:03.000000000 +0200
>> @@ -318,17 +318,24 @@
>>  {
>>  	int result = 0;
>>  	struct mpc_i2c *i2c;
>> +	int set_clock;
>>  
>>  	i2c = kzalloc(sizeof(*i2c), GFP_KERNEL);
>>  	if (!i2c)
>>  		return -ENOMEM;
>>  
>> -	if (of_get_property(op->node, "dfsrr", NULL))
>> -		i2c->flags |= FSL_I2C_DEV_SEPARATE_DFSRR;
>> -
>> -	if (of_device_is_compatible(op->node, "fsl,mpc5200-i2c") ||
>> -			of_device_is_compatible(op->node, "mpc5200-i2c"))
>> -		i2c->flags |= FSL_I2C_DEV_CLOCK_5200;
>> +	if (of_get_property(op->node, "fsl,preserve-clocking", NULL)) {
>> +		set_clock = 0;
>> +	} else {
>> +		set_clock = 1;
>> +
>> +		if (of_get_property(op->node, "dfsrr", NULL))
>> +			i2c->flags |= FSL_I2C_DEV_SEPARATE_DFSRR;
>> +
>> +		if (of_device_is_compatible(op->node, "fsl,mpc5200-i2c") ||
>> +		    of_device_is_compatible(op->node, "mpc5200-i2c"))
>> +			i2c->flags |= FSL_I2C_DEV_CLOCK_5200;
>> +	}
>>  
>>  	init_waitqueue_head(&i2c->queue);
>>  
>> @@ -348,8 +355,9 @@
>>  			goto fail_request;
>>  		}
>>  	}
>> -	
>> -	mpc_i2c_setclock(i2c);
>> +
>> +	if (set_clock)
>> +		mpc_i2c_setclock(i2c);
> 
> Can't we drop 'set_clock' with something like this here?
> 
> +	if (!of_get_property(op->node, "fsl,preserve-clocking", NULL)) {
> +
> +		if (of_get_property(op->node, "dfsrr", NULL))
> +			i2c->flags |= FSL_I2C_DEV_SEPARATE_DFSRR;
> +
> +		if (of_device_is_compatible(op->node, "fsl,mpc5200-i2c") ||
> +		    of_device_is_compatible(op->node, "mpc5200-i2c"))
> +			i2c->flags |= FSL_I2C_DEV_CLOCK_5200;
> +
> +		mpc_i2c_setclock(i2c);
> +	}

No, because the I2C registers are not yet mapped.

Wolfgang.

Re: [PATCH 1/2] powerpc: i2c-mpc: preserve I2C clocking

[Wolfram Sang]

[-- Attachment #1: Type: text/plain, Size: 956 bytes --]


> >> -	
> >> -	mpc_i2c_setclock(i2c);
> >> +
> >> +	if (set_clock)
> >> +		mpc_i2c_setclock(i2c);
> > 
> > Can't we drop 'set_clock' with something like this here?
> > 
> > +	if (!of_get_property(op->node, "fsl,preserve-clocking", NULL)) {
> > +
> > +		if (of_get_property(op->node, "dfsrr", NULL))
> > +			i2c->flags |= FSL_I2C_DEV_SEPARATE_DFSRR;
> > +
> > +		if (of_device_is_compatible(op->node, "fsl,mpc5200-i2c") ||
> > +		    of_device_is_compatible(op->node, "mpc5200-i2c"))
> > +			i2c->flags |= FSL_I2C_DEV_CLOCK_5200;
> > +
> > +		mpc_i2c_setclock(i2c);
> > +	}
> 
> No, because the I2C registers are not yet mapped.

Sorry, I used misleading words :) With 'here' I meant 'at this
position', i.e. insert my above block where mpc_i2c_setclock was used
anyway.

-- 
Pengutronix e.K.                           | Wolfram Sang                |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |

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Re: [PATCH 1/2] powerpc: i2c-mpc: preserve I2C clocking

[Grant Likely]

2009/3/31 Wolfram Sang <w.sang@pengutronix.de>:
>
>> >> -
>> >> - =A0mpc_i2c_setclock(i2c);
>> >> +
>> >> + =A0if (set_clock)
>> >> + =A0 =A0 =A0 =A0 =A0mpc_i2c_setclock(i2c);
>> >
>> > Can't we drop 'set_clock' with something like this here?
>> >
>> > + =A0 if (!of_get_property(op->node, "fsl,preserve-clocking", NULL)) {
>> > +
>> > + =A0 =A0 =A0 =A0 =A0 if (of_get_property(op->node, "dfsrr", NULL))
>> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 i2c->flags |=3D FSL_I2C_DEV_SEPA=
RATE_DFSRR;
>> > +
>> > + =A0 =A0 =A0 =A0 =A0 if (of_device_is_compatible(op->node, "fsl,mpc52=
00-i2c") ||
>> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 of_device_is_compatible(op->node, "mpc52=
00-i2c"))
>> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 i2c->flags |=3D FSL_I2C_DEV_CLOC=
K_5200;
>> > +
>> > + =A0 =A0 =A0 =A0 =A0 mpc_i2c_setclock(i2c);
>> > + =A0 }
>>
>> No, because the I2C registers are not yet mapped.
>
> Sorry, I used misleading words :) With 'here' I meant 'at this
> position', i.e. insert my above block where mpc_i2c_setclock was used
> anyway.

I agree.  The extra flag makes the flow more complex.  The code block
should be moved down.

g.

--=20
Grant Likely, B.Sc., P.Eng.
Secret Lab Technologies Ltd.

Re: [PATCH 1/2] powerpc: i2c-mpc: preserve I2C clocking

[Wolfgang Grandegger]

Grant Likely wrote:
> 2009/3/31 Wolfram Sang <w.sang@pengutronix.de>:
>>>>> -
>>>>> -  mpc_i2c_setclock(i2c);
>>>>> +
>>>>> +  if (set_clock)
>>>>> +          mpc_i2c_setclock(i2c);
>>>> Can't we drop 'set_clock' with something like this here?
>>>>
>>>> +   if (!of_get_property(op->node, "fsl,preserve-clocking", NULL)) {
>>>> +
>>>> +           if (of_get_property(op->node, "dfsrr", NULL))
>>>> +                   i2c->flags |= FSL_I2C_DEV_SEPARATE_DFSRR;
>>>> +
>>>> +           if (of_device_is_compatible(op->node, "fsl,mpc5200-i2c") ||
>>>> +               of_device_is_compatible(op->node, "mpc5200-i2c"))
>>>> +                   i2c->flags |= FSL_I2C_DEV_CLOCK_5200;
>>>> +
>>>> +           mpc_i2c_setclock(i2c);
>>>> +   }
>>> No, because the I2C registers are not yet mapped.
>> Sorry, I used misleading words :) With 'here' I meant 'at this
>> position', i.e. insert my above block where mpc_i2c_setclock was used
>> anyway.
> 
> I agree.  The extra flag makes the flow more complex.  The code block
> should be moved down.

OK, I just resent the patch standalone also including documentation. I
think it can go in immediately without waiting for the full clock
setting patch.

Wolfgang.

PowerPC 460EX AD7416 Temperature Sensor

[Henry Bausley]

Does anyone know if the I2C temperature sensor is functioning on the AMCC 
460EX?
When I do a cat /proc/ad7416 I get the following crash.

Unable to handle kernel paging request for data at address 0x00000000
Faulting instruction address: 0xc02cbe28
Oops: Kernel access of bad area, sig: 11 [#1]
PowerPC 44x Platform
NIP: c02cbe28 LR: c023cec8 CTR: c023d314
REGS: ef107d90 TRAP: 0300   Not tainted  (2.6.28.7)
MSR: 00029000 <EE,ME>  CR: 88000444  XER: 00000000
DEAR: 00000000, ESR: 00000000
TASK = ef8590c0[2611] 'cat' THREAD: ef106000
GPR00: 00000000 ef107e40 ef8590c0 00000000 ef107e9c 00000000 00000c00 
ef107e98
GPR08: 00000000 c0330000 ffffffff c0330000 48000448 1001cb7c 100042bc 
100df49c
GPR16: 00000002 00000400 c032f014 c032efe4 ef107e9c ef107e98 bfffffff 
efb43a00
GPR24: ef61d000 00000000 ef107f20 ef107e98 00000c00 c0400000 00001000 
efb43a00
NIP [c02cbe28] mutex_lock+0x0/0x1c
LR [c023cec8] ad7416_read_temp+0x24/0x80
Call Trace:
[ef107e40] [00000400] 0x400 (unreliable)
[ef107e70] [c023d334] i2c_ad7416_read_proc+0x20/0x70
[ef107e90] [c00e8018] proc_file_read+0x108/0x334
[ef107ee0] [c00e2d3c] proc_reg_read+0x4c/0x70
[ef107ef0] [c00a54e8] vfs_read+0xb4/0x16c
[ef107f10] [c00a58e0] sys_read+0x4c/0x90
[ef107f40] [c000ea88] ret_from_syscall+0x0/0x3c
Instruction dump:
90010014 38000001 90030000 85230004 7f891800 419e000c 80690008 4bd50779
80010014 38210010 7c0803a6 4e800020 <7c001828> 3000ffff 7c00192d 40a2fff4
---[ end trace 774db769c3754abe ]---



**********************************************************
Outbound scan for Spam or Virus by Barracuda at Delta Tau
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RE: PowerPC 460EX AD7416 Temperature Sensor

[Tirumala Reddy Marri]

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Did you have dts entries for IIC in device tree ? also did you have I2C enabled in "make menuconfig" 
"device drivers -> i2c support -->  I2C bus support -> IBM ppc 4xx On chip I2C support " selected. Then you should i2c see an entry /proc/devices . Use that major address and create a device node "mknode /dev/i2c-0 c 89 0" .
 
Write a user level program to access this device. Here is an example user code.
 
----------
cat fan.c
/*  This program is an example of writing and reading an EEPROM device via
    SMBus on a GE Fanuc Embedded Systems, Inc. VMIVME-7809 Single Board
    Computer.
    To compile this program:
        gcc -O vmieep.c -o vmieep

    Before running this program, log in as root, then load the following
    modules using:
       /sbin/modprobe i2c-core
       /sbin/modprobe i2c-dev
       /sbin/modprobe i2c-i801
   Loading the i2c-i801 module will create /dev/i2c-0, with
   permissions = CRW- --- ---.  Either run the vmieep program as root,
   or change the permissions to CRW- RW- RW- as shown:
       chmod 666 /dev/i2c-0
*/

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <errno.h>
#include <fcntl.h>
//#include <linux/i2c.h>
//#include <linux/i2c-dev.h>
#include <sys/time.h>

/* The inline smbus function definitions may or may not be in i2c-dev.h,
   depending on the Linux distribution.  Comment or uncomment the following
   #include as necessary. */
#include "i2c-dev.h" /*  Use the file of lm_sensors  */

#define EEPROM_SIZE   256    /* Adjust for actual number of bytes in EEPROM */
#define EEPROM_SMBUS_ADDR  0x90 /* Do NOT change! */
int gef_eeprom_read(int fd, unsigned char start_offset, unsigned char *buffer,
                    unsigned short buflen);
int gef_eeprom_write(int fd, unsigned char start_offset, unsigned char *buffer,
                    unsigned short buflen);
void gef_msec_delay(unsigned int msecs);

int main(int argc, char *argv[])
{
    int fd;   /* File descriptor initialized with open() */
    int adapter_num = 0;
    int status;
    char filename[20];  /* Name of special device file */
    int i2c_addr = EEPROM_SMBUS_ADDR; /* SMBus address of EEPROM */
    unsigned short offset; /* Which byte to access in the EEPROM */
    unsigned char rbuffer; /* Data read from EEPROM */
    if ((argc < 3) || (argc > 4))
    {
        printf("Usage: fan read <addr> or fan write <addr> <data>\n");
        return 0;
    }
    /* Open the special device file for the SMBus */
    sprintf(filename, "/dev/i2c-%d", adapter_num);
    fd = open(filename, O_RDWR);
    if (fd < 0)
    {
        printf("ERROR: open(%s) failed\n", filename);
        printf("errno = %d, %s\n", errno, strerror(errno));
        return -1;
    }
    //printf("SUCCESS: open(%s) passed\n", filename);

    /* Specify the EEPROM as the device we want to access.
       *** IMPORTANT ***
       The address is actually in the 7 LSBs, so shift
       i2c_addr one bit to the right.*/
    status = ioctl(fd, I2C_SLAVE, i2c_addr>>1);
    if (status < 0)
    {
        printf("ERROR: ioctl(fd, I2C_SLAVE, 0x%02X) failed\n", i2c_addr);
        printf("errno = %d, %s\n", errno, strerror(errno));
        close(fd);
        return -1;
    }
    //printf("SUCCESS: ioctl(fd, I2C_SLAVE, 0x%02X>>1) passed\n", i2c_addr);

    if (strcmp(argv[1],"read") == 0)
    {
        offset = atoi(argv[2]);
        gef_eeprom_read(fd, offset, &rbuffer, 1);
        printf("Offset: %d   Data: %d\n", offset, rbuffer);
    }

    if (strcmp(argv[1],"write") == 0)
    {
        offset = (unsigned char)(atoi(argv[2]));
        rbuffer =(unsigned char)(atoi(argv[3]));
        gef_eeprom_write(fd, offset, &rbuffer, 1);
        printf("Offset: %d   Data: %d\n", offset, rbuffer);
    }

    /* Close the special device file */
    close(fd);
    return 0;
}

//////////////////////////////////////////////////////////////////////////////
//
// Function name : gef_eeprom_read
//
// Description   : Read buflen bytes from the EEPROM beginning at start_offset
//
// Return type   : 0 for success, -1 for failure
//
// Argument      : int fd : File descriptor returned by open()
// Argument      : unsigned char start_offset : Read bytes starting at this
//                     offset in the EEPROM.  The sum of buflen and
//                     start_offset must not exceed the maximum size in bytes
//                     of the EEPROM
// Argument      : unsigned char *buffer : Where to store the bytes read
//                     from the EEPROM.  The buffer must be large enough
//                     to store buflen bytes read from the EEPROM.
// Argument      : unsigned short buflen : The size in bytes of buffer, or
//                     how many bytes to read from the EEPROM.  The sum of
//                     buflen and start_offset must not exceed the maximum
//                     size in bytes of the EEPROM.
//
int gef_eeprom_read(int fd, unsigned char start_offset, unsigned char *buffer,
                    unsigned short buflen)
{
    int offset, index;
    int data;
    for (index=0, offset=start_offset; index<buflen &&
        offset<EEPROM_SIZE; index++, offset++)
    {
        data = i2c_smbus_read_byte_data(fd, offset);
        if (data == -1)
        {
            printf("ERROR: i2c_smbus_read_byte_data(fd, 0x%02X) failed\n",
                offset);
            printf("errno = %d, %s\n", errno, strerror(errno));
            return -1;
        }
        buffer[index] = (unsigned char) (data);
    }
    return 0;
}

//////////////////////////////////////////////////////////////////////////////
//
// Function name : gef_eeprom_write
//
// Description   : Write buflen bytes to the EEPROM beginning at start_offset
//
// Return type   : 0 for success, -1 for failure
//
// Argument      : int fd : File descriptor returned by open()
// Argument      : unsigned char start_offset : Write bytes starting at this
//                     offset in the EEPROM.  The sum of buflen and
//                     start_offset must not exceed the maximum size in bytes
//                     of the EEPROM
// Argument      : unsigned char *buffer : Where to get the bytes to write
//                     to the EEPROM.
// Argument      : unsigned short buflen : The size in bytes of buffer.
//                     The sum of buflen and start_offset must not exceed the
//                     maximum size in bytes of the EEPROM.
//
int gef_eeprom_write(int fd, unsigned char start_offset, unsigned char *buffer,
                    unsigned short buflen)
{
    int offset, index;
    int status;
    for (index=0, offset=start_offset; index<buflen &&
        offset<EEPROM_SIZE; index++, offset++)
    {
        status = i2c_smbus_write_byte_data(fd, offset, buffer[index]);
        if (status < 0)
        {
            printf("ERROR: i2c_smbus_write_byte_data(fd, 0x%02X, 0x%02X) failed\n",
                offset, buffer[index]);
            printf("errno = %d, %s\n", errno, strerror(errno));
            return -1;
        }
        /* Delay while the byte write completes */
        gef_msec_delay(10);
    }
    return 0;
}

//////////////////////////////////////////////////////////////////////////////
//
// Function name : gef_msec_delay
//
// Description   : Delay for a number of milliseconds before returning
//
// Return type   : void
//
// Argument      : unsigned int msecs : The number of milliseconds to delay
//
void gef_msec_delay(unsigned int msecs)
{
    struct timeval s_current, s_start;
    struct timezone tz;
    unsigned int current, start;

    /* Get initial time */
    gettimeofday(&s_start, &tz);
    start = s_start.tv_sec*1000000 + s_start.tv_usec;
    /* Loop until msecs time have elapsed */
    do
    {
        gettimeofday(&s_current, &tz);
        current = s_current.tv_sec*1000000 + s_current.tv_usec;
    } while ((current-start) < (msecs*1000));
}

-------------

________________________________

From: linuxppc-dev-bounces+tmarri=amcc.com@ozlabs.org on behalf of Henry Bausley
Sent: Tue 3/31/2009 5:41 PM
To: linuxppc-dev@ozlabs.org
Subject: PowerPC 460EX AD7416 Temperature Sensor



Does anyone know if the I2C temperature sensor is functioning on the AMCC
460EX?
When I do a cat /proc/ad7416 I get the following crash.

Unable to handle kernel paging request for data at address 0x00000000
Faulting instruction address: 0xc02cbe28
Oops: Kernel access of bad area, sig: 11 [#1]
PowerPC 44x Platform
NIP: c02cbe28 LR: c023cec8 CTR: c023d314
REGS: ef107d90 TRAP: 0300   Not tainted  (2.6.28.7)
MSR: 00029000 <EE,ME>  CR: 88000444  XER: 00000000
DEAR: 00000000, ESR: 00000000
TASK = ef8590c0[2611] 'cat' THREAD: ef106000
GPR00: 00000000 ef107e40 ef8590c0 00000000 ef107e9c 00000000 00000c00
ef107e98
GPR08: 00000000 c0330000 ffffffff c0330000 48000448 1001cb7c 100042bc
100df49c
GPR16: 00000002 00000400 c032f014 c032efe4 ef107e9c ef107e98 bfffffff
efb43a00
GPR24: ef61d000 00000000 ef107f20 ef107e98 00000c00 c0400000 00001000
efb43a00
NIP [c02cbe28] mutex_lock+0x0/0x1c
LR [c023cec8] ad7416_read_temp+0x24/0x80
Call Trace:
[ef107e40] [00000400] 0x400 (unreliable)
[ef107e70] [c023d334] i2c_ad7416_read_proc+0x20/0x70
[ef107e90] [c00e8018] proc_file_read+0x108/0x334
[ef107ee0] [c00e2d3c] proc_reg_read+0x4c/0x70
[ef107ef0] [c00a54e8] vfs_read+0xb4/0x16c
[ef107f10] [c00a58e0] sys_read+0x4c/0x90
[ef107f40] [c000ea88] ret_from_syscall+0x0/0x3c
Instruction dump:
90010014 38000001 90030000 85230004 7f891800 419e000c 80690008 4bd50779
80010014 38210010 7c0803a6 4e800020 <7c001828> 3000ffff 7c00192d 40a2fff4
---[ end trace 774db769c3754abe ]---



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[-- Attachment #2: Type: text/html, Size: 17110 bytes --]

[PATCH 2/2] powerpc: i2c-mpc: make I2C bus speed configurable

[Wolfgang Grandegger]

This patch makes the I2C bus speed configurable by using the I2C node
property "clock-frequency". If the property is not defined, the old
fixed clock settings will be used for backward comptibility.

The generic I2C clock properties, especially the CPU-specific source
clock pre-scaler are defined via the OF match table:

  static const struct of_device_id mpc_i2c_of_match[] = {
	{.compatible = "fsl,mpc5200b-i2c",
	 .data = (void *)FSL_I2C_DEV_CLOCK_5200, },
	{.compatible = "fsl,mpc5200-i2c",
	 .data = (void *)FSL_I2C_DEV_CLOCK_5200, },
	{.compatible = "fsl,mpc8313-i2c",
	 .data = (void *)FSL_I2C_DEV_SEPARATE_DFSRR, },
	{.compatible = "fsl,mpc8543-i2c",
	 .data = (void *)(FSL_I2C_DEV_SEPARATE_DFSRR |
			  FSL_I2C_DEV_CLOCK_DIV2), },
	{.compatible = "fsl,mpc8544-i2c",
	 .data = (void *)(FSL_I2C_DEV_SEPARATE_DFSRR |
			  FSL_I2C_DEV_CLOCK_DIV23), },
	/* Backward compatibility */
	{.compatible = "fsl-i2c", },
	{},
  };

The "data" field defines the relevant I2C flags for the comptible CPU.

It used arch-specific tables and functions to determine the proper
Freqency Divider Register (fdr).

Furthermore dev_dbg() and dev_info() are now used to profit from a more
comprehensive output.

Signed-off-by: Wolfgang Grandegger <wg@grandegger.com>
---
 arch/powerpc/platforms/52xx/mpc52xx_common.c |   48 ++++++++++++
 arch/powerpc/sysdev/fsl_soc.c                |   90 +++++++++++++++++++++++
 drivers/i2c/busses/i2c-mpc.c                 |  104 +++++++++++++++++++--------
 include/linux/fsl_devices.h                  |    6 +
 4 files changed, 221 insertions(+), 27 deletions(-)

Index: linux-2.6/drivers/i2c/busses/i2c-mpc.c
===================================================================
--- linux-2.6.orig/drivers/i2c/busses/i2c-mpc.c	2009-03-31 13:28:03.000000000 +0200
+++ linux-2.6/drivers/i2c/busses/i2c-mpc.c	2009-03-31 13:38:01.355720989 +0200
@@ -20,12 +20,14 @@
 #include <linux/of_platform.h>
 #include <linux/of_i2c.h>
 
-#include <asm/io.h>
+#include <linux/io.h>
 #include <linux/fsl_devices.h>
 #include <linux/i2c.h>
 #include <linux/interrupt.h>
 #include <linux/delay.h>
 
+#include <sysdev/fsl_soc.h>
+
 #define DRV_NAME "mpc-i2c"
 
 #define MPC_I2C_FDR 	0x04
@@ -50,6 +52,7 @@
 #define CSR_RXAK 0x01
 
 struct mpc_i2c {
+	struct device *dev;
 	void __iomem *base;
 	u32 interrupt;
 	wait_queue_head_t queue;
@@ -105,7 +108,7 @@
 		while (!(readb(i2c->base + MPC_I2C_SR) & CSR_MIF)) {
 			schedule();
 			if (time_after(jiffies, orig_jiffies + timeout)) {
-				pr_debug("I2C: timeout\n");
+				dev_dbg(i2c->dev, "timeout\n");
 				writeccr(i2c, 0);
 				result = -EIO;
 				break;
@@ -119,10 +122,10 @@
 			(i2c->interrupt & CSR_MIF), timeout * HZ);
 
 		if (unlikely(result < 0)) {
-			pr_debug("I2C: wait interrupted\n");
+			dev_dbg(i2c->dev, "wait interrupted\n");
 			writeccr(i2c, 0);
 		} else if (unlikely(!(i2c->interrupt & CSR_MIF))) {
-			pr_debug("I2C: wait timeout\n");
+			dev_dbg(i2c->dev, "wait timeout\n");
 			writeccr(i2c, 0);
 			result = -ETIMEDOUT;
 		}
@@ -135,17 +138,17 @@
 		return result;
 
 	if (!(x & CSR_MCF)) {
-		pr_debug("I2C: unfinished\n");
+		dev_dbg(i2c->dev, "unfinished\n");
 		return -EIO;
 	}
 
 	if (x & CSR_MAL) {
-		pr_debug("I2C: MAL\n");
+		dev_dbg(i2c->dev, "MAL\n");
 		return -EIO;
 	}
 
 	if (writing && (x & CSR_RXAK)) {
-		pr_debug("I2C: No RXAK\n");
+		dev_dbg(i2c->dev, "No RXAK\n");
 		/* generate stop */
 		writeccr(i2c, CCR_MEN);
 		return -EIO;
@@ -153,17 +156,38 @@
 	return 0;
 }
 
-static void mpc_i2c_setclock(struct mpc_i2c *i2c)
+static void mpc_i2c_setclock(struct device_node *node,
+			     struct mpc_i2c *i2c, u32 clock)
 {
-	/* Set clock and filters */
-	if (i2c->flags & FSL_I2C_DEV_SEPARATE_DFSRR) {
-		writeb(0x31, i2c->base + MPC_I2C_FDR);
-		writeb(0x10, i2c->base + MPC_I2C_DFSRR);
-	} else if (i2c->flags & FSL_I2C_DEV_CLOCK_5200)
-		writeb(0x3f, i2c->base + MPC_I2C_FDR);
-	else
-		writel(0x1031, i2c->base + MPC_I2C_FDR);
-}
+	int fdr;
+
+	fdr = fsl_i2c_get_fdr(node, clock, i2c->flags);
+
+	if (i2c->flags & FSL_I2C_DEV_CLOCK_5200) {
+		pr_debug("I2C: old fdr=%d\n", readb(i2c->base + MPC_I2C_FDR));
+		if (fdr < 0)
+			fdr = 0x3f; /* backward compatibility */
+		writeb(fdr & 0xff, i2c->base + MPC_I2C_FDR);
+		dev_info("clock %d Hz (fdr=%d)\n", clock, fdr);
+	} else {
+		if (fdr < 0)
+			fdr = 0x1031; /* backward compatibility */
+		if (i2c->flags & FSL_I2C_DEV_SEPARATE_DFSRR) {
+			pr_debug("I2C: old dfsrr=%d fdr=%d\n",
+			       readb(i2c->base + MPC_I2C_DFSRR),
+			       readb(i2c->base + MPC_I2C_FDR));
+			writeb(fdr & 0xff, i2c->base + MPC_I2C_FDR);
+			writeb((fdr >> 8) & 0xff, i2c->base + MPC_I2C_DFSRR);
+			dev_info("clock %d Hz (dfsrr=%d fdr=%d)\n",
+			       clock, fdr >> 8, fdr & 0xff);
+		} else {
+			pr_debug("I2C: old fdr=%d\n",
+				 readl(i2c->base + MPC_I2C_FDR));
+			writel(fdr & 0xffff, i2c->base + MPC_I2C_FDR);
+			dev_info("clock %d Hz (fdr=%d)\n", clock, fdr);
+		}
+	}
+ }
 
 static void mpc_i2c_start(struct mpc_i2c *i2c)
 {
@@ -267,12 +291,12 @@
 	/* Allow bus up to 1s to become not busy */
 	while (readb(i2c->base + MPC_I2C_SR) & CSR_MBB) {
 		if (signal_pending(current)) {
-			pr_debug("I2C: Interrupted\n");
+			dev_dbg(i2c->dev, "interrupted\n");
 			writeccr(i2c, 0);
 			return -EINTR;
 		}
 		if (time_after(jiffies, orig_jiffies + HZ)) {
-			pr_debug("I2C: timeout\n");
+			dev_dbg(i2c->dev, "timeout\n");
 			if (readb(i2c->base + MPC_I2C_SR) ==
 			    (CSR_MCF | CSR_MBB | CSR_RXAK))
 				mpc_i2c_fixup(i2c);
@@ -283,9 +307,10 @@
 
 	for (i = 0; ret >= 0 && i < num; i++) {
 		pmsg = &msgs[i];
-		pr_debug("Doing %s %d bytes to 0x%02x - %d of %d messages\n",
-			 pmsg->flags & I2C_M_RD ? "read" : "write",
-			 pmsg->len, pmsg->addr, i + 1, num);
+		dev_dbg(i2c->dev,
+			"doing %s %d bytes to 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 =
 			    mpc_read(i2c, pmsg->addr, pmsg->buf, pmsg->len, i);
@@ -316,9 +341,12 @@
 
 static int __devinit fsl_i2c_probe(struct of_device *op, const struct of_device_id *match)
 {
-	int result = 0;
 	struct mpc_i2c *i2c;
+	const u32 *prop;
+	u32 clock = 0;
 	int set_clock;
+	int result = 0;
+	int plen;
 
 	i2c = kzalloc(sizeof(*i2c), GFP_KERNEL);
 	if (!i2c)
@@ -328,7 +356,11 @@
 		set_clock = 0;
 	} else {
 		set_clock = 1;
+		prop = of_get_property(op->node, "clock-frequency", &plen);
+		if (prop && plen == sizeof(u32))
+			clock = *prop;
 
+		/* Backwards compatibility */
 		if (of_get_property(op->node, "dfsrr", NULL))
 			i2c->flags |= FSL_I2C_DEV_SEPARATE_DFSRR;
 
@@ -356,11 +388,15 @@
 		}
 	}
 
-	if (set_clock)
-		mpc_i2c_setclock(i2c);
+	if (set_clock) {
+		if (match->data)
+			i2c->flags = (u32)match->data;
+		mpc_i2c_setclock(op->node, i2c, clock);
+	}
 
 	dev_set_drvdata(&op->dev, i2c);
 
+	i2c->dev = &op->dev;
 	i2c->adap = mpc_ops;
 	i2c_set_adapdata(&i2c->adap, i2c);
 	i2c->adap.dev.parent = &op->dev;
@@ -402,9 +438,23 @@
 };
 
 static const struct of_device_id mpc_i2c_of_match[] = {
-	{.compatible = "fsl-i2c",},
+	{.compatible = "fsl,mpc5200b-i2c",
+	 .data = (void *)FSL_I2C_DEV_CLOCK_5200, },
+	{.compatible = "fsl,mpc5200-i2c",
+	 .data = (void *)FSL_I2C_DEV_CLOCK_5200, },
+	{.compatible = "fsl,mpc8313-i2c",
+	 .data = (void *)FSL_I2C_DEV_SEPARATE_DFSRR, },
+	{.compatible = "fsl,mpc8543-i2c",
+	 .data = (void *)(FSL_I2C_DEV_SEPARATE_DFSRR |
+			  FSL_I2C_DEV_CLOCK_DIV2), },
+	{.compatible = "fsl,mpc8544-i2c",
+	 .data = (void *)(FSL_I2C_DEV_SEPARATE_DFSRR |
+			  FSL_I2C_DEV_CLOCK_DIV23), },
+	/* Backward compatibility */
+	{.compatible = "fsl-i2c", },
 	{},
 };
+
 MODULE_DEVICE_TABLE(of, mpc_i2c_of_match);
 
 
@@ -425,7 +475,7 @@
 
 	rv = of_register_platform_driver(&mpc_i2c_driver);
 	if (rv)
-		printk(KERN_ERR DRV_NAME 
+		printk(KERN_ERR DRV_NAME
 		       " of_register_platform_driver failed (%i)\n", rv);
 	return rv;
 }
Index: linux-2.6/arch/powerpc/sysdev/fsl_soc.c
===================================================================
--- linux-2.6.orig/arch/powerpc/sysdev/fsl_soc.c	2009-03-31 13:25:08.000000000 +0200
+++ linux-2.6/arch/powerpc/sysdev/fsl_soc.c	2009-03-31 13:34:40.531721011 +0200
@@ -102,6 +102,96 @@
 }
 EXPORT_SYMBOL(fsl_get_sys_freq);
 
+#ifdef CONFIG_I2C_MPC
+static const struct fsl_i2c_divider {
+	u16 divider;
+	u16 fdr;	/* including dfsrr */
+} fsl_i2c_8xxx_dividers[] = {
+	{160, 0x0120}, {192, 0x0121}, {224, 0x0122}, {256, 0x0123},
+	{288, 0x0100}, {320, 0x0101}, {352, 0x0601}, {384, 0x0102},
+	{416, 0x0602}, {448, 0x0126}, {480, 0x0103}, {512, 0x0127},
+	{544, 0x0b03}, {576, 0x0104}, {608, 0x1603}, {640, 0x0105},
+	{672, 0x2003}, {704, 0x0b05}, {736, 0x2b03}, {768, 0x0106},
+	{800, 0x3603}, {832, 0x0b06}, {896, 0x012a}, {960, 0x0107},
+	{1024, 0x012b}, {1088, 0x1607}, {1152, 0x0108}, {1216, 0x2b07},
+	{1280, 0x0109}, {1408, 0x1609}, {1536, 0x010a}, {1664, 0x160a},
+	{1792, 0x012e}, {1920, 0x010b}, {2048, 0x012f}, {2176, 0x2b0b},
+	{2304, 0x010c}, {2560, 0x010d}, {2816, 0x2b0d}, {3072, 0x010e},
+	{3328, 0x2b0e}, {3584, 0x0132}, {3840, 0x010f}, {4096, 0x0133},
+	{4608, 0x0110}, {5120, 0x0111}, {6144, 0x0112}, {7168, 0x0136},
+	{7680, 0x0113}, {8192, 0x0137}, {9216, 0x0114}, {10240, 0x0115},
+	{12288, 0x0116}, {14336, 0x013a}, {15360, 0x0117}, {16384, 0x013b},
+	{18432, 0x0118}, {20480, 0x0119}, {24576, 0x011a}, {28672, 0x013e},
+	{30720, 0x011b}, {32768, 0x013f}, {36864, 0x011c}, {40960, 0x011d},
+	{49152, 0x011e}, {61440, 0x011f}
+};
+
+u32 fsl_i2c_get_sec_cfg(void)
+{
+	struct device_node *node = NULL;
+	u32 __iomem *reg;
+	u32 val = 0;
+
+	node = of_find_node_by_name(NULL, "global-utilities");
+	if (node) {
+		const u32 *prop = of_get_property(node, "reg", NULL);
+		if (prop) {
+			/*
+			 * Map and check POR Device Status Register 2
+			 * (PORDEVSR2) at 0xE0014
+			 */
+			reg = ioremap(get_immrbase() + *prop + 0x14, 0x4);
+			if (!reg)
+				printk(KERN_ERR
+				       "Error: couldn't map PORDEVSR2\n");
+			else
+				val = in_be32(reg);
+			iounmap(reg);
+		}
+	}
+	if (node)
+		of_node_put(node);
+
+	return val;
+}
+
+int fsl_i2c_get_fdr(struct device_node *node, u32 i2c_clock, u32 i2c_flags)
+{
+	const struct fsl_i2c_divider *div = NULL;
+	u32 src_clock, divider;
+	int i;
+
+	if (!i2c_clock)
+		return -EINVAL;
+
+	/* Determine divider value */
+	src_clock = fsl_get_sys_freq();
+	divider =  src_clock / i2c_clock;
+	if (i2c_flags & FSL_I2C_DEV_CLOCK_DIV2)
+		divider /= 2;
+	else if (i2c_flags & FSL_I2C_DEV_CLOCK_DIV3)
+		divider /= 3;
+	else if (i2c_flags & FSL_I2C_DEV_CLOCK_DIV23)
+		divider /= fsl_i2c_get_sec_cfg() ? 3 : 2;
+
+	pr_debug("I2C: src_clock=%d clock=%d flags=%#x divider=%d\n",
+		 src_clock, i2c_clock, i2c_flags, divider);
+
+	/*
+	 * We want to choose an FDR/DFSR that generates an I2C bus speed that
+	 * is equal to or lower than the requested speed.
+	 */
+	for (i = 0; i < ARRAY_SIZE(fsl_i2c_8xxx_dividers); i++) {
+		div = &fsl_i2c_8xxx_dividers[i];
+		if (div->divider >= divider)
+			break;
+	}
+
+	return div ? (int)div->fdr : -EINVAL;
+}
+EXPORT_SYMBOL(fsl_i2c_get_fdr);
+#endif /* CONFIG_I2C_MPC */
+
 #if defined(CONFIG_CPM2) || defined(CONFIG_QUICC_ENGINE) || defined(CONFIG_8xx)
 
 static u32 brgfreq = -1;
Index: linux-2.6/include/linux/fsl_devices.h
===================================================================
--- linux-2.6.orig/include/linux/fsl_devices.h	2009-03-31 13:25:08.000000000 +0200
+++ linux-2.6/include/linux/fsl_devices.h	2009-03-31 13:28:54.305720748 +0200
@@ -68,6 +68,12 @@
 /* Flags related to I2C device features */
 #define FSL_I2C_DEV_SEPARATE_DFSRR	0x00000001
 #define FSL_I2C_DEV_CLOCK_5200		0x00000002
+#define FSL_I2C_DEV_CLOCK_DIV2		0x00000004
+#define FSL_I2C_DEV_CLOCK_DIV3		0x00000008
+#define FSL_I2C_DEV_CLOCK_DIV23		0x00000010
+
+extern int fsl_i2c_get_fdr(struct device_node *node,
+			   u32 i2c_clock, u32 i2c_flags);
 
 enum fsl_usb2_operating_modes {
 	FSL_USB2_MPH_HOST,
Index: linux-2.6/arch/powerpc/platforms/52xx/mpc52xx_common.c
===================================================================
--- linux-2.6.orig/arch/powerpc/platforms/52xx/mpc52xx_common.c	2009-03-31 13:25:08.000000000 +0200
+++ linux-2.6/arch/powerpc/platforms/52xx/mpc52xx_common.c	2009-03-31 13:28:54.309718526 +0200
@@ -225,3 +225,51 @@
 
 	while (1);
 }
+
+/**
+ * fsl_i2c_get_fdr: get calculate and return I2 frequency divider register
+ */
+static const struct mpc52xx_i2c_divider {
+	u16 divider;
+	u16 fdr;	/* including dfsrr */
+} mpc52xx_i2_dividers[] = {
+	{20, 0x20}, {22, 0x21}, {24, 0x22}, {26, 0x23},
+	{28, 0x24}, {30, 0x01}, {32, 0x25}, {34, 0x02},
+	{36, 0x26}, {40, 0x27}, {44, 0x04}, {48, 0x28},
+	{56, 0x29}, {64, 0x2a}, {68, 0x07}, {72, 0x2b},
+	{80, 0x2c}, {88, 0x09}, {96, 0x2d}, {104, 0x0a},
+	{112, 0x2e}, {128, 0x2f}, {144, 0x0c}, {160, 0x30},
+	{192, 0x31}, {224, 0x32}, {240, 0x0f}, {256, 0x33},
+	{288, 0x10}, {320, 0x34}, {384, 0x35}, {448, 0x36},
+	{480, 0x13}, {512, 0x37}, {576, 0x14}, {640, 0x38},
+	{768, 0x39}, {896, 0x3a}, {960, 0x17}, {1024, 0x3b},
+	{1152, 0x18}, {1280, 0x3c}, {1536, 0x3d}, {1792, 0x3e},
+	{1920, 0x1b}, {2048, 0x3f}, {2304, 0x1c}, {2560, 0x1d},
+	{3072, 0x1e}, {3840, 0x1f}
+};
+
+int fsl_i2c_get_fdr(struct device_node *node, u32 i2c_clock, u32 i2c_flags)
+{
+	const struct fsl_i2c_divider *div = NULL;
+	u32 divider;
+	int i;
+
+	if (!i2c_clock)
+		return -EINVAL;
+
+	/* Determine divider value */
+	divider = mpc52xx_find_ipb_freq(node) / i2c_clock;
+
+	/*
+	 * We want to choose an FDR/DFSR that generates an I2C bus speed that
+	 * is equal to or lower than the requested speed.
+	 */
+	for (i = 0; i < ARRAY_SIZE(fsl_i2c_8xxx_dividers); i++) {
+		div = &fsl_i2c_8xxx_dividers[i];
+		if (div->divider >= divider)
+			break;
+	}
+
+	return div ? (int)div->fdr : -EINVAL;
+}
+EXPORT_SYMBOL(fsl_i2c_get_fdr);

[PATCH 0/2] test

[Wolfgang Grandegger]

test 

[PATCH 1/2] powerpc: i2c-mpc: preserve I2C clocking

[Wolfgang Grandegger]

The I2c node property "fsl,preserve-clocking" allows to overtake the
clock settings from the boot loader and avoids the hard-coded setting.

Signed-off-by: Wolfgang Grandegger <wg@grandegger.com>
---
 drivers/i2c/busses/i2c-mpc.c |   24 ++++++++++++++++--------
 1 file changed, 16 insertions(+), 8 deletions(-)

Index: linux-2.6/drivers/i2c/busses/i2c-mpc.c
===================================================================
--- linux-2.6.orig/drivers/i2c/busses/i2c-mpc.c	2009-03-31 13:25:08.000000000 +0200
+++ linux-2.6/drivers/i2c/busses/i2c-mpc.c	2009-03-31 13:28:03.000000000 +0200
@@ -318,17 +318,24 @@
 {
 	int result = 0;
 	struct mpc_i2c *i2c;
+	int set_clock;
 
 	i2c = kzalloc(sizeof(*i2c), GFP_KERNEL);
 	if (!i2c)
 		return -ENOMEM;
 
-	if (of_get_property(op->node, "dfsrr", NULL))
-		i2c->flags |= FSL_I2C_DEV_SEPARATE_DFSRR;
-
-	if (of_device_is_compatible(op->node, "fsl,mpc5200-i2c") ||
-			of_device_is_compatible(op->node, "mpc5200-i2c"))
-		i2c->flags |= FSL_I2C_DEV_CLOCK_5200;
+	if (of_get_property(op->node, "fsl,preserve-clocking", NULL)) {
+		set_clock = 0;
+	} else {
+		set_clock = 1;
+
+		if (of_get_property(op->node, "dfsrr", NULL))
+			i2c->flags |= FSL_I2C_DEV_SEPARATE_DFSRR;
+
+		if (of_device_is_compatible(op->node, "fsl,mpc5200-i2c") ||
+		    of_device_is_compatible(op->node, "mpc5200-i2c"))
+			i2c->flags |= FSL_I2C_DEV_CLOCK_5200;
+	}
 
 	init_waitqueue_head(&i2c->queue);
 
@@ -348,8 +355,9 @@
 			goto fail_request;
 		}
 	}
-	
-	mpc_i2c_setclock(i2c);
+
+	if (set_clock)
+		mpc_i2c_setclock(i2c);
 
 	dev_set_drvdata(&op->dev, i2c);
 

Re: [PATCH 1/2] powerpc: i2c-mpc: preserve I2C clocking

[David Gibson]

On Tue, Mar 31, 2009 at 02:43:39PM +0200, Wolfgang Grandegger wrote:
> The I2c node property "fsl,preserve-clocking" allows to overtake the
> clock settings from the boot loader and avoids the hard-coded setting.

Hrm.  This is dubious.  The device tree should generally describe
hardware, not OS/driver behaviour which is what this appears to be
doing.  There are exceptions, but you need to justify them.

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

Re: [PATCH 1/2] powerpc: i2c-mpc: preserve I2C clocking

[Wolfgang Grandegger]

David Gibson wrote:
> On Tue, Mar 31, 2009 at 02:43:39PM +0200, Wolfgang Grandegger wrote:
>> The I2c node property "fsl,preserve-clocking" allows to overtake the
>> clock settings from the boot loader and avoids the hard-coded setting.
> 
> Hrm.  This is dubious.  The device tree should generally describe
> hardware, not OS/driver behaviour which is what this appears to be
> doing.  There are exceptions, but you need to justify them.

I think the purpose of this property is clear. How would you provide
that functionality instead? I suggested that a "clock-frequency = <0>"
property should do the trick but Grant preferred to be more explicit.

Wolfgang.

Re: [PATCH 1/2] powerpc: i2c-mpc: preserve I2C clocking

[David Gibson]

On Wed, Apr 01, 2009 at 09:40:13AM +0200, Wolfgang Grandegger wrote:
> David Gibson wrote:
> > On Tue, Mar 31, 2009 at 02:43:39PM +0200, Wolfgang Grandegger wrote:
> >> The I2c node property "fsl,preserve-clocking" allows to overtake the
> >> clock settings from the boot loader and avoids the hard-coded setting.
> > 
> > Hrm.  This is dubious.  The device tree should generally describe
> > hardware, not OS/driver behaviour which is what this appears to be
> > doing.  There are exceptions, but you need to justify them.
> 
> I think the purpose of this property is clear. How would you provide
> that functionality instead? I suggested that a "clock-frequency = <0>"
> property should do the trick but Grant preferred to be more
> explicit.

I'm not saying the meaning is unclear, I'm saying it's describing
something that the device tree isn't meant to describe.  AFAICT it's
telling the driver what to do with the device, not a property of the
device itself.

Now, there are cases where it's acceptable to put this sort of
information in the device tree, because it's the least nasty available
solution (flash partition information for example).  But you need to
justify it, if that's so.

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson