From: Sylvain Munaut <tnt@246tnt•com>
To: Adrian Cox <adrian@humboldt•co.uk>
Cc: mcclintock@freescale•com,
Embedded Linux PPC list <linuxppc-embedded@lists•linuxppc.org>,
"Kumar K. Gala" <kumar.gala@motorola•com>,
Matthew McClintock <mcclintock@motorola•com>
Subject: Re: [PATCH][RFC]Updated MPC I2C driver
Date: Fri, 02 Jul 2004 00:32:32 +0200 [thread overview]
Message-ID: <40E49100.2060501@246tNt.com> (raw)
In-Reply-To: <1088717127.28598.197.camel@localhost>
[-- Attachment #1: Type: text/plain, Size: 2269 bytes --]
Adrian Cox wrote:
>It seems that the MPC107 is happy with 8 bit accesses to the registers,
>so here's another version of the patch. This also changes the time
>calculations to use time_after().
>
>
The MPC5200 seems happy too ;) There is a eeprom on the board and it's
detected and I can access it. If I find a soldering iron, I'll hook up
another I2C device to test other devices.
Some gotchas though :
- The FDR computation is completly different. Here is the code I
attached the code I used in my I2C driver. Basically, it takes as
argument the desired I2C clock rate ( was a module parameter ) and the
internal bus frequency and then compute the FDR.
- During the scan, the first bus is scanned without devices and the
error when debug is active is I2C_MAL. From the moment the eeprom is
detected, the error code become I2C_NORXACK for the address wihout
device. Included dmesg
drivers/i2c/busses/i2c-mpc.c: Doing write 0 bytes to 0x57 - 1 of 1 messages
drivers/i2c/busses/i2c-mpc.c: I2C: MAL
i2c_adapter i2c-1: found normal i2c_range entry for adapter 1, addr 0050
i2c_adapter i2c-1: master_xfer: with 1 msgs.
drivers/i2c/busses/i2c-mpc.c: Doing write 0 bytes to 0x50 - 1 of 1 messages
i2c_adapter i2c-1: master_xfer: with 1 msgs.
drivers/i2c/busses/i2c-mpc.c: Doing write 0 bytes to 0x50 - 1 of 1 messages
i2c_adapter i2c-1: client [eeprom] registered to adapter
registering 1-0050
i2c_adapter i2c-1: found normal i2c_range entry for adapter 1, addr 0051
i2c_adapter i2c-1: master_xfer: with 1 msgs.
drivers/i2c/busses/i2c-mpc.c: Doing write 0 bytes to 0x51 - 1 of 1 messages
drivers/i2c/busses/i2c-mpc.c: I2C: No RXAK
i2c_adapter i2c-1: found normal i2c_range entry for adapter 1, addr 0052
i2c_adapter i2c-1: master_xfer: with 1 msgs.
- The interrupt bit. BTW, on what event should the interrupt be fired ?
(I did my test without any interrupts )
>This still leaves the interrupt handling register of the MPC5200
>unsolved. I suggest introducing another flag for the MPC5200, and adding
>a small piece of extra setup code.
>
>
Yes, something like FS_I2C_IS_MPC52xx
Another remark : The register setup are done at every _start. Couldn't
they be done once for all during init ( just after the probe, call a
init_hardware functions ).
Sylvain Munaut
[-- Attachment #2: fdr_mpc5200.c --]
[-- Type: text/x-csrc, Size: 864 bytes --]
static int
mpc52xx_i2c_get_best_fdr(int ipb_freq, int i2c_speed)
{
/* Consts */
const struct { int scl2tap; int tap2tap; } x2taps[] = {
{ 4, 1 },
{ 4, 2 },
{ 6, 4 },
{ 6, 8 },
{ 14, 16 },
{ 30, 32 },
{ 62, 64 },
{ 126, 128 },
};
const int scl_taps[] = { 9, 10, 12, 15, 5, 6, 7, 8 };
int best_i, best_j, i, j;
int scl;
int best_diff = 0x7fffffff, diff;
int fdr;
for ( i=7 ; i>=0 ; i-- ) {
for ( j=0 ; j<8 ; j++ ) {
scl = 2 * (x2taps[i].scl2tap + ((scl_taps[j] - 1) * x2taps[i].tap2tap) + 2);
/* We only want frequency BELOW or EQUAL to */
/* the target frequency */
diff = i2c_speed * scl - ipb_freq;
if ( (diff > 0) && (diff < best_diff) ) {
best_diff = diff;
best_i = i;
best_j = j;
}
}
}
fdr = ((best_i << 2) | (best_j & 0x03) | ((best_j & 0x04) << 5)) & 0x3f;
return fdr;
}
next prev parent reply other threads:[~2004-07-01 22:32 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-07-01 18:19 [PATCH][RFC]Updated MPC I2C driver Adrian Cox
2004-07-01 14:59 ` Matthew McClintock
2004-07-01 21:25 ` Adrian Cox
2004-07-01 22:32 ` Sylvain Munaut [this message]
2004-07-02 9:05 ` Adrian Cox
2004-07-02 11:01 ` Sylvain Munaut
2004-07-02 13:44 ` Adrian Cox
2004-07-02 15:11 ` Sylvain Munaut
2004-07-01 18:59 ` Eugene Surovegin
2004-07-01 19:20 ` Sylvain Munaut
2004-07-01 15:48 ` Matthew McClintock
2004-07-01 21:07 ` Sylvain Munaut
2004-07-01 20:54 ` Adrian Cox
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=40E49100.2060501@246tNt.com \
--to=tnt@246tnt$(echo .)com \
--cc=adrian@humboldt$(echo .)co.uk \
--cc=kumar.gala@motorola$(echo .)com \
--cc=linuxppc-embedded@lists$(echo .)linuxppc.org \
--cc=mcclintock@freescale$(echo .)com \
--cc=mcclintock@motorola$(echo .)com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox