[PATCH] I2C: MV64XYZ: Add Device Tree support
Andrew Lunn
andrew at lunn.ch
Fri Jul 20 13:00:57 EDT 2012
Extends the driver to get properties from device tree. Rather than
pass the N & M factors in DT, use the more standard clock-frequency
property. Calculate N & M at run time. In order to do this, we need to
know tclk. So the driver uses clk_get() etc in order to get the clock
and clk_get_rate() to determine the tclk rate. Not all platforms
however have CLK, so some #ifdefery is needed to ensure the driver
still compiles when CLK is not available.
Signed-off-by: Andrew Lunn <andrew at lunn.ch>
---
- Replaced the timeout property in DT, with a hard coded 1 second.
- Put all the OF code together.
- Split the ARM parts from the driver itself.
- Dropped Sebastian Hesselbarth Acked-by, since the changes are not trivial.
- Change MV64XXX to MV64XYZ in the Subject to try to get it past the list
spam filter.
This patch and the ARM counter part patch, plus all the DT changes to
make us of it can be found in:
git://github.com/lunn/linux.git v3.5-rc7-for-next-v5
This patch is not yet rebased on i2c-embedded/for-next. I will do this
once there is a general acceptance of this patch.
Documentation/devicetree/bindings/i2c/mrvl-i2c.txt | 19 ++-
drivers/i2c/busses/i2c-mv64xxx.c | 135 +++++++++++++++++++-
2 files changed, 148 insertions(+), 6 deletions(-)
diff --git a/Documentation/devicetree/bindings/i2c/mrvl-i2c.txt b/Documentation/devicetree/bindings/i2c/mrvl-i2c.txt
index b891ee2..0f79450 100644
--- a/Documentation/devicetree/bindings/i2c/mrvl-i2c.txt
+++ b/Documentation/devicetree/bindings/i2c/mrvl-i2c.txt
@@ -1,4 +1,4 @@
-* I2C
+* Marvell MMP I2C controller
Required properties :
@@ -32,3 +32,20 @@ Examples:
interrupts = <58>;
};
+* Marvell MV64XXX I2C controller
+
+Required properties :
+
+ - reg : Offset and length of the register set for the device
+ - compatible : Should be "marvell,mv64xxx-i2c"
+ - interrupts : The interrupt number
+ - clock-frequency : Desired I2C bus clock frequency in Hz.
+
+Examples:
+
+ i2c at 11000 {
+ compatible = "marvell,mv64xxx-i2c";
+ reg = <0x11000 0x20>;
+ interrupts = <29>;
+ clock-frequency = <100000>;
+ };
diff --git a/drivers/i2c/busses/i2c-mv64xxx.c b/drivers/i2c/busses/i2c-mv64xxx.c
index 4f44a33..e5449be 100644
--- a/drivers/i2c/busses/i2c-mv64xxx.c
+++ b/drivers/i2c/busses/i2c-mv64xxx.c
@@ -18,6 +18,11 @@
#include <linux/mv643xx_i2c.h>
#include <linux/platform_device.h>
#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/of_irq.h>
+#include <linux/of_i2c.h>
+#include <linux/clk.h>
+#include <linux/err.h>
/* Register defines */
#define MV64XXX_I2C_REG_SLAVE_ADDR 0x00
@@ -98,6 +103,9 @@ struct mv64xxx_i2c_data {
int rc;
u32 freq_m;
u32 freq_n;
+#if defined(CONFIG_HAVE_CLK)
+ struct clk *clk;
+#endif
wait_queue_head_t waitq;
spinlock_t lock;
struct i2c_msg *msg;
@@ -521,6 +529,83 @@ mv64xxx_i2c_unmap_regs(struct mv64xxx_i2c_data *drv_data)
drv_data->reg_base_p = 0;
}
+#ifdef CONFIG_OF
+static int __devinit
+mv64xxx_calc_freq(const int tclk, const int n, const int m)
+{
+ return tclk / (10 * (m + 1) * (2 << n));
+}
+
+static bool __devinit
+mv64xxx_find_baud_factors(const int req_freq, const int tclk, int *best_n,
+ int *best_m)
+{
+ int freq, delta, best_delta = INT_MAX;
+ int m, n;
+
+ for (n = 0; n <= 7; n++)
+ for (m = 0; m <= 15; m++) {
+ freq = mv64xxx_calc_freq(tclk, n, m);
+ delta = req_freq - freq;
+ if (delta >= 0 && delta < best_delta) {
+ *best_m = m;
+ *best_n = n;
+ best_delta = delta;
+ }
+ if (best_delta == 0)
+ return true;
+ }
+ if (best_delta == INT_MAX)
+ return false;
+ return true;
+}
+
+static int __devinit
+mv64xxx_of_config(struct mv64xxx_i2c_data *drv_data,
+ struct device_node *np)
+{
+ int bus_freq;
+ int tclk;
+ int rc = 0;
+
+ /* CLK is mandatory when using DT to describe the i2c bus. We
+ * need to know tclk in order to calculate bus clock
+ * factors.
+ */
+#if !defined(CONFIG_HAVE_CLK)
+ /* Have OF but no CLK */
+ rc = -ENODEV;
+#else
+ if (IS_ERR(drv_data->clk)) {
+ rc = -ENODEV;
+ goto out;
+ }
+ tclk = clk_get_rate(drv_data->clk);
+ of_property_read_u32(np, "clock-frequency", &bus_freq);
+ if (!mv64xxx_find_baud_factors(bus_freq, tclk,
+ &drv_data->freq_n, &drv_data->freq_m)) {
+ rc = -EINVAL;
+ goto out;
+ }
+ drv_data->irq = irq_of_parse_and_map(np, 0);
+
+ /* Its not yet defined how timeouts will be specified in device tree.
+ * So hard code the value to 1 second.
+ */
+ drv_data->adapter.timeout = HZ;
+out:
+ return rc;
+#endif
+}
+#else /* CONFIG_OF */
+static int __devinit
+mv64xxx_of_config(struct mv64xxx_i2c_data *drv_data,
+ struct device_node *np)
+{
+ return -ENODEV;
+}
+#endif /* CONFIG_OF */
+
static int __devinit
mv64xxx_i2c_probe(struct platform_device *pd)
{
@@ -528,7 +613,7 @@ mv64xxx_i2c_probe(struct platform_device *pd)
struct mv64xxx_i2c_pdata *pdata = pd->dev.platform_data;
int rc;
- if ((pd->id != 0) || !pdata)
+ if ((!pdata && !pd->dev.of_node) || (pdata && (pd->id != 0)))
return -ENODEV;
drv_data = kzalloc(sizeof(struct mv64xxx_i2c_data), GFP_KERNEL);
@@ -546,19 +631,36 @@ mv64xxx_i2c_probe(struct platform_device *pd)
init_waitqueue_head(&drv_data->waitq);
spin_lock_init(&drv_data->lock);
- drv_data->freq_m = pdata->freq_m;
- drv_data->freq_n = pdata->freq_n;
- drv_data->irq = platform_get_irq(pd, 0);
+#if defined(CONFIG_HAVE_CLK)
+ /* Not all platforms have a clk */
+ drv_data->clk = clk_get(&pd->dev, NULL);
+ if (!IS_ERR(drv_data->clk)) {
+ clk_prepare(drv_data->clk);
+ clk_enable(drv_data->clk);
+ }
+#endif
+ if (pdata) {
+ drv_data->freq_m = pdata->freq_m;
+ drv_data->freq_n = pdata->freq_n;
+ drv_data->irq = platform_get_irq(pd, 0);
+ drv_data->adapter.timeout = msecs_to_jiffies(pdata->timeout);
+ }
+ if (pd->dev.of_node) {
+ rc = mv64xxx_of_config(drv_data, pd->dev.of_node);
+ if (rc)
+ goto exit_unmap_regs;
+ }
if (drv_data->irq < 0) {
rc = -ENXIO;
goto exit_unmap_regs;
}
+
drv_data->adapter.dev.parent = &pd->dev;
drv_data->adapter.algo = &mv64xxx_i2c_algo;
drv_data->adapter.owner = THIS_MODULE;
drv_data->adapter.class = I2C_CLASS_HWMON | I2C_CLASS_SPD;
- drv_data->adapter.timeout = msecs_to_jiffies(pdata->timeout);
drv_data->adapter.nr = pd->id;
+ drv_data->adapter.dev.of_node = pd->dev.of_node;
platform_set_drvdata(pd, drv_data);
i2c_set_adapdata(&drv_data->adapter, drv_data);
@@ -577,11 +679,20 @@ mv64xxx_i2c_probe(struct platform_device *pd)
goto exit_free_irq;
}
+ of_i2c_register_devices(&drv_data->adapter);
+
return 0;
exit_free_irq:
free_irq(drv_data->irq, drv_data);
exit_unmap_regs:
+#if defined(CONFIG_HAVE_CLK)
+ /* Not all platforms have a clk */
+ if (!IS_ERR(drv_data->clk)) {
+ clk_disable(drv_data->clk);
+ clk_unprepare(drv_data->clk);
+ }
+#endif
mv64xxx_i2c_unmap_regs(drv_data);
exit_kfree:
kfree(drv_data);
@@ -597,17 +708,31 @@ mv64xxx_i2c_remove(struct platform_device *dev)
rc = i2c_del_adapter(&drv_data->adapter);
free_irq(drv_data->irq, drv_data);
mv64xxx_i2c_unmap_regs(drv_data);
+#if defined(CONFIG_HAVE_CLK)
+ /* Not all platforms have a clk */
+ if (!IS_ERR(drv_data->clk)) {
+ clk_disable(drv_data->clk);
+ clk_unprepare(drv_data->clk);
+ }
+#endif
kfree(drv_data);
return rc;
}
+static const struct of_device_id mv64xxx_i2c_of_match_table[] __devinitdata = {
+ { .compatible = "marvell,mv64xxx-i2c", },
+ {}
+};
+MODULE_DEVICE_TABLE(of, mv64xxx_i2c_of_match_table);
+
static struct platform_driver mv64xxx_i2c_driver = {
.probe = mv64xxx_i2c_probe,
.remove = __devexit_p(mv64xxx_i2c_remove),
.driver = {
.owner = THIS_MODULE,
.name = MV64XXX_I2C_CTLR_NAME,
+ .of_match_table = of_match_ptr(mv64xxx_i2c_of_match_table),
},
};
--
1.7.10
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