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From 3239987e97227ed6dcad81498b98f6e40c2a81a8 Mon Sep 17 00:00:00 2001
From: Devon Fyson <devonfyson@gmail.com>
Date: Wed, 30 Dec 2015 16:40:47 -0500
Subject: [PATCH] Extend clock timeout, fix modprobe baudrate parameter.
Set the BSC_CLKT clock streching timeout to 35ms as per SMBus specs.\n- Increase priority of baudrate parameter passed to modprobe (in /etc/modprobe.d/*.conf or command line). Currently custom baudrates don't work because they are overridden by clock-frequency in the platform_device passed to the function.
---
drivers/i2c/busses/i2c-bcm2708.c | 45 ++++++++++++++++++++++++++--------------
1 file changed, 29 insertions(+), 16 deletions(-)
--- a/drivers/i2c/busses/i2c-bcm2708.c
+++ b/drivers/i2c/busses/i2c-bcm2708.c
@@ -71,7 +71,8 @@
#define DRV_NAME "bcm2708_i2c"
-static unsigned int baudrate = CONFIG_I2C_BCM2708_BAUDRATE;
+static unsigned int baudrate_default = CONFIG_I2C_BCM2708_BAUDRATE;
+static unsigned int baudrate;
module_param(baudrate, uint, S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP);
MODULE_PARM_DESC(baudrate, "The I2C baudrate");
@@ -87,6 +88,7 @@ struct bcm2708_i2c {
int irq;
struct clk *clk;
u32 cdiv;
+ u32 clk_tout;
struct completion done;
@@ -126,7 +128,7 @@ static inline void bcm2708_bsc_fifo_fill
static inline int bcm2708_bsc_setup(struct bcm2708_i2c *bi)
{
- u32 cdiv, s;
+ u32 cdiv, s, clk_tout;
u32 c = BSC_C_I2CEN | BSC_C_INTD | BSC_C_ST | BSC_C_CLEAR_1;
int wait_loops = I2C_WAIT_LOOP_COUNT;
@@ -134,12 +136,14 @@ static inline int bcm2708_bsc_setup(stru
* Use the value that we cached in the probe.
*/
cdiv = bi->cdiv;
+ clk_tout = bi->clk_tout;
if (bi->msg->flags & I2C_M_RD)
c |= BSC_C_INTR | BSC_C_READ;
else
c |= BSC_C_INTT;
+ bcm2708_wr(bi, BSC_CLKT, clk_tout);
bcm2708_wr(bi, BSC_DIV, cdiv);
bcm2708_wr(bi, BSC_A, bi->msg->addr);
bcm2708_wr(bi, BSC_DLEN, bi->msg->len);
@@ -312,21 +316,24 @@ static int bcm2708_i2c_probe(struct plat
struct bcm2708_i2c *bi;
struct i2c_adapter *adap;
unsigned long bus_hz;
- u32 cdiv;
-
- if (pdev->dev.of_node) {
- u32 bus_clk_rate;
- pdev->id = of_alias_get_id(pdev->dev.of_node, "i2c");
- if (pdev->id < 0) {
- dev_err(&pdev->dev, "alias is missing\n");
- return -EINVAL;
+ u32 cdiv, clk_tout;
+
+ if (!baudrate) {
+ baudrate = baudrate_default;
+ if (pdev->dev.of_node) {
+ u32 bus_clk_rate;
+ pdev->id = of_alias_get_id(pdev->dev.of_node, "i2c");
+ if (pdev->id < 0) {
+ dev_err(&pdev->dev, "alias is missing\n");
+ return -EINVAL;
+ }
+ if (!of_property_read_u32(pdev->dev.of_node,
+ "clock-frequency", &bus_clk_rate))
+ baudrate = bus_clk_rate;
+ else
+ dev_warn(&pdev->dev,
+ "Could not read clock-frequency property\n");
}
- if (!of_property_read_u32(pdev->dev.of_node,
- "clock-frequency", &bus_clk_rate))
- baudrate = bus_clk_rate;
- else
- dev_warn(&pdev->dev,
- "Could not read clock-frequency property\n");
}
regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
@@ -417,7 +424,13 @@ static int bcm2708_i2c_probe(struct plat
cdiv = 0xffff;
baudrate = bus_hz / cdiv;
}
+
+ clk_tout = 35/1000*baudrate; //35ms timeout as per SMBus specs.
+ if (clk_tout > 0xffff)
+ clk_tout = 0xffff;
+
bi->cdiv = cdiv;
+ bi->clk_tout = clk_tout;
dev_info(&pdev->dev, "BSC%d Controller at 0x%08lx (irq %d) (baudrate %d)\n",
pdev->id, (unsigned long)regs->start, irq, baudrate);
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