[U-Boot] [PATCH 3/3] fsl_i2c: Impl. AN2919, rev 5 to calculate FDR/DFSR

Joakim Tjernlund
2009-09-17T09:07:17Z

The latest AN2919 has changed the way FDR/DFSR should be calculated.
Update the driver according to spec. However, Condition 2
is not accounted for as it is not clear how to do so.

Signed-off-by: Joakim Tjernlund <Joakim.Tjernlund@transmode.se>
---
drivers/i2c/fsl_i2c.c | 90 ++++++++++++++++++++++++++++++-------------------
1 files changed, 55 insertions(+), 35 deletions(-)

diff --git a/drivers/i2c/fsl_i2c.c b/drivers/i2c/fsl_i2c.c
index 0c5f6be..78f21c7 100644
--- a/drivers/i2c/fsl_i2c.c
+++ b/drivers/i2c/fsl_i2c.c
@@ -100,29 +100,9 @@ static const struct fsl_i2c *i2c_dev[2] = {
*/
static const struct {
unsigned short divider;
-#ifdef __PPC__
- u8 dfsr;
-#endif
u8 fdr;
} fsl_i2c_speed_map[] = {
-#ifdef __PPC__
- {160, 1, 32}, {192, 1, 33}, {224, 1, 34}, {256, 1, 35},
- {288, 1, 0}, {320, 1, 1}, {352, 6, 1}, {384, 1, 2}, {416, 6, 2},
- {448, 1, 38}, {480, 1, 3}, {512, 1, 39}, {544, 11, 3}, {576, 1, 4},
- {608, 22, 3}, {640, 1, 5}, {672, 32, 3}, {704, 11, 5}, {736, 43, 3},
- {768, 1, 6}, {800, 54, 3}, {832, 11, 6}, {896, 1, 42}, {960, 1, 7},
- {1024, 1, 43}, {1088, 22, 7}, {1152, 1, 8}, {1216, 43, 7}, {1280, 1, 9},
- {1408, 22, 9}, {1536, 1, 10}, {1664, 22, 10}, {1792, 1, 46},
- {1920, 1, 11}, {2048, 1, 47}, {2176, 43, 11}, {2304, 1, 12},
- {2560, 1, 13}, {2816, 43, 13}, {3072, 1, 14}, {3328, 43, 14},
- {3584, 1, 50}, {3840, 1, 15}, {4096, 1, 51}, {4608, 1, 16},
- {5120, 1, 17}, {6144, 1, 18}, {7168, 1, 54}, {7680, 1, 19},
- {8192, 1, 55}, {9216, 1, 20}, {10240, 1, 21}, {12288, 1, 22},
- {14336, 1, 58}, {15360, 1, 23}, {16384, 1, 59}, {18432, 1, 24},
- {20480, 1, 25}, {24576, 1, 26}, {28672, 1, 62}, {30720, 1, 27},
- {32768, 1, 63}, {36864, 1, 28}, {40960, 1, 29}, {49152, 1, 30},
- {61440, 1, 31}, {-1, 1, 31}
-#elif defined(__M68K__)
+#ifdef __M68K__
{20, 32}, {22, 33}, {24, 34}, {26, 35},
{28, 0}, {28, 36}, {30, 1}, {32, 37},
{34, 2}, {36, 38}, {40, 3}, {40, 39},
@@ -158,7 +138,6 @@ static unsigned int set_i2c_bus_speed(const struct fsl_i2c *dev,
unsigned int i2c_clk, unsigned int speed)
{
unsigned short divider = min(i2c_clk / speed, (unsigned short) -1);
- unsigned int i;

/*
* We want to choose an FDR/DFSR that generates an I2C bus speed that
@@ -166,31 +145,72 @@ static unsigned int set_i2c_bus_speed(const struct fsl_i2c *dev,
* want the first divider that is equal to or greater than the
* calculated divider.
*/
-
- for (i = 0; i < ARRAY_SIZE(fsl_i2c_speed_map); i++)
- if (fsl_i2c_speed_map[i].divider >= divider) {
- u8 fdr;
#ifdef __PPC__
- u8 dfsr;
+ u8 dfsr, fdr = 0x31; /* Default if no FDR found */
+ /* a, b and dfsr matches identifiers A,B and C respectively in AN2919 */
+ unsigned short a, b, ga, gb;
+ unsigned long c_div, est_div;
+
#ifdef CONFIG_FSL_I2C_CUSTOM_DFSR
- dfsr = CONFIG_FSL_I2C_CUSTOM_DFSR;
+ dfsr = CONFIG_FSL_I2C_CUSTOM_DFSR;
#else
- dfsr = fsl_i2c_speed_map[i].dfsr;
-#endif
- writeb(dfsr, &dev->dfsrr); /* set default filter */
+ /* Condition 1: dfsr <= 50/T */
+ dfsr = (5 * (i2c_clk / 1000)) / 100000;
#endif
#ifdef CONFIG_FSL_I2C_CUSTOM_FDR
- fdr = CONFIG_FSL_I2C_CUSTOM_FDR;
- speed = i2c_clk / divider; /* Fake something */
+ fdr = CONFIG_FSL_I2C_CUSTOM_FDR;
+ speed = i2c_clk / divider; /* Fake something */
#else
+ debug("Requested speed:%d, i2c_clk:%d\n", speed, i2c_clk);
+ if (!dfsr)
+ dfsr = 1;
+
+ est_div = ~0;
+ for (ga = 0x4, a = 10; a <= 30; ga++, a += 2) {
+ for (gb = 0; gb < 8; gb++) {
+ b = 16 << gb;
+ c_div = b * (a + ((3*dfsr)/b)*2);
+ if ((c_div > divider) && (c_div < est_div)) {
+ unsigned short bin_gb, bin_ga;
+
+ est_div = c_div;
+ bin_gb = gb << 2;
+ bin_ga = (ga & 0x3) | ((ga & 0x4) << 3);
+ fdr = bin_gb | bin_ga;
+ speed = i2c_clk / est_div;
+ debug("FDR:0x%.2x, div:%ld, ga:0x%x, gb:0x%x, "
+ "a:%d, b:%d, speed:%d\n",
+ fdr, est_div, ga, gb, a, b, speed);
+ /* Condition 2 not accounted for */
+ debug("Tr <= %d ns\n",
+ (b - 3 * dfsr) * 1000000 /
+ (i2c_clk / 1000));
+ }
+ }
+ if (a == 20)
+ a += 2;
+ if (a == 24)
+ a += 4;
+ }
+ debug("divider:%d, est_div:%ld, DFSR:%d\n", divider, est_div, dfsr);
+ debug("FDR:0x%.2x, speed:%d\n", fdr, speed);
+#endif
+ writeb(dfsr, &dev->dfsrr); /* set default filter */
+ writeb(fdr, &dev->fdr); /* set bus speed */
+#else
+ unsigned int i;
+
+ for (i = 0; i < ARRAY_SIZE(fsl_i2c_speed_map); i++)
+ if (fsl_i2c_speed_map[i].divider >= divider) {
+ u8 fdr;
+
fdr = fsl_i2c_speed_map[i].fdr;
speed = i2c_clk / fsl_i2c_speed_map[i].divider;
-#endif
writeb(fdr, &dev->fdr); /* set bus speed */

break;
}
-
+#endif
return speed;
}

--
1.6.4.3