This patch disables the newly introduced internal pull-up feature in
OMAP3630, to use only the external HW resitor >= 470 Ohm for the
assured functionality in HS mode.
While testing the I2C in High Speed mode, it was discovered that
without a proper pull-up resitor, there is data corruption during
multi-byte transfers. RTC(time_set) test case was used for testing.
>From the analysis done, it was concluded that ideally we need a pull-up
of 1.6 K Ohm (recomended) or atleast 470 Ohm or greater for assured
performance in HS mode.
Signed-off-by: Moiz Sonasath <m-sonasath@xxxxxx>
Signed-off-by: Allen Pais <allen.pais@xxxxxx>
Signed-off-by: Vikram Pandita <vikram.pandita@xxxxxx>
---
arch/arm/mach-omap2/i2c.c | 24 ++++++++++++++++++++++++
arch/arm/plat-omap/include/plat/control.h | 14 ++++++++++++++
2 files changed, 38 insertions(+), 0 deletions(-)
diff --git a/arch/arm/mach-omap2/i2c.c b/arch/arm/mach-omap2/i2c.c
index 789ca8c..2e6eb28 100644
--- a/arch/arm/mach-omap2/i2c.c
+++ b/arch/arm/mach-omap2/i2c.c
@@ -22,6 +22,7 @@
#include <plat/cpu.h>
#include <plat/i2c.h>
#include <plat/mux.h>
+#include <plat/control.h>
#include "mux.h"
@@ -52,5 +53,28 @@ int __init omap_register_i2c_bus(int bus_id, u32 clkrate,
omap_mux_init_signal(mux_name, OMAP_PIN_INPUT);
}
+ /* Disable OMAP 3630 internal pull-ups for all I2Ci */
+ if (cpu_is_omap3630() && !(omap_ctrl_readl(OMAP343X_CONTROL_PROG_IO1) & OMAP3630_PRG_I2C1_PULLUPRESX)) {
+
+ u32 prog_io;
+
+ prog_io = omap_ctrl_readl(OMAP343X_CONTROL_PROG_IO1);
+ /* Program (bit 19)=1 to disable internal pull-up on I2C1 */
+ prog_io |= OMAP3630_PRG_I2C1_PULLUPRESX;
+ /* Program (bit 0)=1 to disable internal pull-up on I2C2 */
+ prog_io |= OMAP3630_PRG_I2C2_PULLUPRESX;
+ omap_ctrl_writel(prog_io, OMAP343X_CONTROL_PROG_IO1);
+
+ prog_io = omap_ctrl_readl(OMAP36XX_CONTROL_PROG_IO2);
+ /* Program (bit 7)=1 to disable internal pull-up on I2C3 */
+ prog_io |= OMAP3630_PRG_I2C3_PULLUPRESX;
+ omap_ctrl_writel(prog_io, OMAP36XX_CONTROL_PROG_IO2);
+
+ prog_io = omap_ctrl_readl(OMAP36XX_CONTROL_PROG_IO_WKUP1);
+ /* Program (bit 5)=1 to disable internall pull-up on I2C4(SR) */
+ prog_io |= OMAP3630_PRG_SR_PULLUPRESX;
+ omap_ctrl_writel(prog_io, OMAP36XX_CONTROL_PROG_IO_WKUP1);
+ }
+
return omap_plat_register_i2c_bus(bus_id, clkrate, info, len);
}
diff --git a/arch/arm/plat-omap/include/plat/control.h b/arch/arm/plat-omap/include/plat/control.h
index 2074473..9e58d8e 100644
--- a/arch/arm/plat-omap/include/plat/control.h
+++ b/arch/arm/plat-omap/include/plat/control.h
@@ -169,6 +169,9 @@
#define AM35XX_CONTROL_IP_SW_RESET (OMAP2_CONTROL_GENERAL + 0x0328)
#define AM35XX_CONTROL_IPSS_CLK_CTRL (OMAP2_CONTROL_GENERAL + 0x032C)
+/* 36xx-only CONTROL_GENERAL register offsets */
+#define OMAP36XX_CONTROL_PROG_IO2 (OMAP2_CONTROL_GENERAL + 0x0198)
+
/* 34xx PADCONF register offsets */
#define OMAP343X_PADCONF_ETK(i) (OMAP2_CONTROL_PADCONFS + 0x5a8 + \
(i)*2)
@@ -200,6 +203,9 @@
#define OMAP343X_CONTROL_WKUP_DEBOBS3 (OMAP343X_CONTROL_GENERAL_WKUP + 0x014)
#define OMAP343X_CONTROL_WKUP_DEBOBS4 (OMAP343X_CONTROL_GENERAL_WKUP + 0x018)
+/* 36xx-only GENERAL_WKUP register offsets */
+#define OMAP36XX_CONTROL_PROG_IO_WKUP1 (OMAP343X_CONTROL_GENERAL_WKUP + 0x020)
+
/* 34xx D2D idle-related pins, handled by PM core */
#define OMAP3_PADCONF_SAD2D_MSTANDBY 0x250
#define OMAP3_PADCONF_SAD2D_IDLEACK 0x254
@@ -250,6 +256,8 @@
#define OMAP2_PBIASLITEVMODE0 (1 << 0)
/* CONTROL_PROG_IO1 bits */
+#define OMAP3630_PRG_I2C2_PULLUPRESX (1 << 0)
+#define OMAP3630_PRG_I2C1_PULLUPRESX (1 << 19)
#define OMAP3630_PRG_SDMMC1_SPEEDCTRL (1 << 20)
/* CONTROL_IVA2_BOOTMOD bits */
@@ -257,6 +265,12 @@
#define OMAP3_IVA2_BOOTMOD_MASK (0xf << 0)
#define OMAP3_IVA2_BOOTMOD_IDLE (0x1 << 0)
+/* CONTROL_PROG_IO2 bits on omap3630 */
+#define OMAP3630_PRG_I2C3_PULLUPRESX (1 << 7)
+
+/* CONTROL_PROG_IO_WKUP1 bits on omap3630 */
+#define OMAP3630_PRG_SR_PULLUPRESX (1 << 5)
+
/* CONTROL_PADCONF_X bits */
#define OMAP3_PADCONF_WAKEUPEVENT0 (1 << 15)
#define OMAP3_PADCONF_WAKEUPENABLE0 (1 << 14)
--
1.5.6.3
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