i2c: Blackfin TWI: make sure we don't end up with a CLKDIV=0
Michael Hennerich [Mon, 18 May 2009 12:14:41 +0000 (08:14 -0400)]
Make sure we don't end up with an invalid CLKDIV=0 in case someone
specifies 20kHz SCL or less (5 * 1024 / 20 = 0x100).

Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Bryan Wu <cooloney@kernel.org>
[ben-linux@fluff.org: shortened subject line]
Signed-off-by: Ben Dooks <ben-linux@fluff.org>

drivers/i2c/busses/Kconfig
drivers/i2c/busses/i2c-bfin-twi.c

index f1c6ca7..c8460fa 100644 (file)
@@ -298,7 +298,7 @@ config I2C_BLACKFIN_TWI
 config I2C_BLACKFIN_TWI_CLK_KHZ
        int "Blackfin TWI I2C clock (kHz)"
        depends on I2C_BLACKFIN_TWI
-       range 10 400
+       range 21 400
        default 50
        help
          The unit of the TWI clock is kHz.
index fc548b3..77cafb6 100644 (file)
@@ -614,6 +614,7 @@ static int i2c_bfin_twi_probe(struct platform_device *pdev)
        struct i2c_adapter *p_adap;
        struct resource *res;
        int rc;
+       unsigned int clkhilow;
 
        iface = kzalloc(sizeof(struct bfin_twi_iface), GFP_KERNEL);
        if (!iface) {
@@ -675,10 +676,14 @@ static int i2c_bfin_twi_probe(struct platform_device *pdev)
        /* Set TWI internal clock as 10MHz */
        write_CONTROL(iface, ((get_sclk() / 1024 / 1024 + 5) / 10) & 0x7F);
 
+       /*
+        * We will not end up with a CLKDIV=0 because no one will specify
+        * 20kHz SCL or less in Kconfig now. (5 * 1024 / 20 = 0x100)
+        */
+       clkhilow = 5 * 1024 / CONFIG_I2C_BLACKFIN_TWI_CLK_KHZ;
+
        /* Set Twi interface clock as specified */
-       write_CLKDIV(iface, ((5*1024 / CONFIG_I2C_BLACKFIN_TWI_CLK_KHZ)
-                       << 8) | ((5*1024 / CONFIG_I2C_BLACKFIN_TWI_CLK_KHZ)
-                       & 0xFF));
+       write_CLKDIV(iface, (clkhilow << 8) | clkhilow);
 
        /* Enable TWI */
        write_CONTROL(iface, read_CONTROL(iface) | TWI_ENA);