Re: Fwd: [PATCH 1/3] i2c: Add Device Tree support to the NomadikI2C driver
From: Lee Jones
Date: Fri Jun 15 2012 - 08:45:14 EST
On 15/06/12 12:50, Srinidhi Kasagar wrote:
[...]
From: Lee Jones<lee.jones@xxxxxxxxxx>
Date: Tue, 17 Apr 2012 16:04:13 +0100
Subject: [PATCH 1/1] i2c: Add Device Tree support to the Nomadik I2C driver
Here we apply the bindings required for successful Device Tree
probing of the i2c-nomadik driver. We also apply a fall-back
configuration in case either one is not provided, or a required
element is missing from the one supplied.
Cc: linux-i2c@xxxxxxxxxxxxxxx
Signed-off-by: Lee Jones<lee.jones@xxxxxxxxxx>
---
drivers/i2c/busses/i2c-nomadik.c | 82 +++++++++++++++++++++++++++++++++++++-
1 file changed, 80 insertions(+), 2 deletions(-)
diff --git a/drivers/i2c/busses/i2c-nomadik.c b/drivers/i2c/busses/i2c-nomadik.c
index a92440d..58e8114 100644
--- a/drivers/i2c/busses/i2c-nomadik.c
+++ b/drivers/i2c/busses/i2c-nomadik.c
@@ -23,6 +23,7 @@
#include<linux/io.h>
#include<linux/regulator/consumer.h>
#include<linux/pm_runtime.h>
+#include<linux/of.h>
#include<plat/i2c.h>
@@ -899,15 +900,86 @@ static const struct i2c_algorithm nmk_i2c_algo = {
.functionality = nmk_i2c_functionality
};
+static struct nmk_i2c_controller u8500_i2c = {
+ /*
+ * Slave data setup time; 250ns, 100ns, and 10ns, which
+ * is 14, 6 and 2 respectively for a 48Mhz i2c clock.
+ */
+ .slsu = 0xe,
+ .tft = 1, /* Tx FIFO threshold */
+ .rft = 8, /* Rx FIFO threshold */
+ .clk_freq = 100000, /* std. mode operation */
+ .timeout = 200, /* Slave response timeout(ms) */
+ .sm = I2C_FREQ_MODE_FAST,
How is this possible? you are setting clk_freq as 100kb/s and mode
as fast mode which is supposed to be 400kb/s.
That's not how I read it:
enum i2c_freq_mode {
I2C_FREQ_MODE_STANDARD, /* up to 100 Kb/s */
I2C_FREQ_MODE_FAST, /* up to 400 Kb/s */
I2C_FREQ_MODE_HIGH_SPEED, /* up to 3.4 Mb/s */
I2C_FREQ_MODE_FAST_PLUS, /* up to 1 Mb/s */
};
The operative words here are "up to".
+};
+
+static int __devinit
+nmk_i2c_of_probe(struct device_node *np, struct nmk_i2c_controller *pdata)
+{
+ of_property_read_u32(np, "clock-frequency", (u32*)&pdata->clk_freq);
+ if (!pdata->clk_freq) {
+ pr_warn("%s: Clock frequency not found\n", np->full_name);
+ return -EINVAL;
+ }
+
+ of_property_read_u32(np, "stericsson,slsu", (u32*)&pdata->slsu);
+ if (!pdata->slsu) {
+ pr_warn("%s: Data line delay not found\n", np->full_name);
+ return -EINVAL;
+ }
+
+ of_property_read_u32(np, "stericsson,tft", (u32*)&pdata->tft);
+ if (!pdata->tft) {
+ pr_warn("%s: Tx FIFO threshold not found\n", np->full_name);
+ return -EINVAL;
+ }
+
+ of_property_read_u32(np, "stericsson,rft", (u32*)&pdata->rft);
+ if (!pdata->rft) {
+ pr_warn("%s: Rx FIFO threshold not found\n", np->full_name);
+ return -EINVAL;
+ }
+
+ of_property_read_u32(np, "stericsson,timeout", (u32*)&pdata->timeout);
+ if (!pdata->timeout) {
+ pr_warn("%s: Timeout not found\n", np->full_name);
+ return -EINVAL;
+ }
+
+ if (of_get_property(np, "stericsson,i2c_freq_mode_fast", NULL))
+ pdata->sm = I2C_FREQ_MODE_FAST;
+ else
+ pdata->sm = I2C_FREQ_MODE_STANDARD;
The controller has more modes like fast mode plus and high speed mode. You can't make
assumptions like this.
These are currently unsupported. Read the comments in the file:
/*
* set the speed mode. Currently we support
* only standard and fast mode of operation
* TODO - support for fast mode plus (up to 1Mb/s)
* and high speed (up to 3.4 Mb/s)
*/
I can add a similar comment here if it make you feel better?
+
+ return 0;
+}
+
static int __devinit nmk_i2c_probe(struct platform_device *pdev)
{
int ret = 0;
struct resource *res;
- struct nmk_i2c_controller *pdata =
- pdev->dev.platform_data;
+ struct nmk_i2c_controller *pdata = pdev->dev.platform_data;
+ struct device_node *np = pdev->dev.of_node;
struct nmk_i2c_dev *dev;
struct i2c_adapter *adap;
+ if (np) {
+ if (!pdata) {
+ pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
+ if (!pdata) {
+ ret = -ENOMEM;
+ goto err_no_mem;
+ }
+ }
+ ret = nmk_i2c_of_probe(np, pdata);
+ if (ret)
+ kfree(pdata);
+ }
+
+ if (!pdata)
+ /* No i2c configuration found, using the default. */
+ pdata =&u8500_i2c;
There are redundant fallback configurations exists in the driver. You might need to remove
those, if you want to fallback here.
I only see a fall-back for clk_freq. Are there others?
+
dev = kzalloc(sizeof(struct nmk_i2c_dev), GFP_KERNEL);
if (!dev) {
dev_err(&pdev->dev, "cannot allocate memory\n");
@@ -1038,11 +1110,17 @@ static int __devexit nmk_i2c_remove(struct platform_device *pdev)
return 0;
}
+static const struct of_device_id nmk_gpio_match[] = {
+ { .compatible = "st,nomadik-i2c", },
+ {},
+};
+
static struct platform_driver nmk_i2c_driver = {
.driver = {
.owner = THIS_MODULE,
.name = DRIVER_NAME,
.pm =&nmk_i2c_pm,
+ .of_match_table = nmk_gpio_match,
},
.probe = nmk_i2c_probe,
.remove = __devexit_p(nmk_i2c_remove),
--
1.7.9.5
Kind regards,
Lee
--
Lee Jones
Linaro ST-Ericsson Landing Team Lead
M: +44 77 88 633 515
Linaro.org â Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog
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