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

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Submitter Wolfgang Grandegger
Date March 31, 2009, 12:50 p.m.
Message ID <20090331125451.600446749@denx.de>
Download mbox | patch
Permalink /patch/25404/
State Superseded, archived
Delegated to: Kumar Gala
Headers show

Comments

Wolfgang Grandegger - March 31, 2009, 12:50 p.m.
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(-)
Wolfram Sang - March 31, 2009, 1:39 p.m.
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
Wolfgang Grandegger - March 31, 2009, 1:47 p.m.
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.
Wolfram Sang - March 31, 2009, 1:56 p.m.
> >> -	
> >> -	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.
Grant Likely - March 31, 2009, 3:44 p.m.
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.

g.
Wolfgang Grandegger - March 31, 2009, 8:05 p.m.
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.
Henry Bausley - April 1, 2009, 12:41 a.m.
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
**********************************************************
Tirumala Reddy Marri - April 1, 2009, 2:10 a.m.
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));
}

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

Patch

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);