i2c: imx: add runtime pm support to improve the performance
In our former i2c driver, i2c clk is enabled and disabled in
xfer function, which contributes to power saving. However,
the clk enable process brings a busy wait delay until the core
is stable. As a result, the performance is sacrificed.
To weigh the power consumption and i2c bus performance, runtime
pm is the good solution for it. The clk is enabled when a i2c
transfer starts, and disabled after a specifically defined delay.
If CONFIG_PM is disabled the net result of this patch is that the
clock is never disabled.
Without the patch the test case (many eeprom reads) executes with approx:
real 1m7.735s
user 0m0.488s
sys 0m20.040s
With the patch the same test case (many eeprom reads) executes with approx:
real 0m54.241s
user 0m0.440s
sys 0m5.920s
Signed-off-by: Fugang Duan <B38611@freescale.com>
Signed-off-by: Gao Pan <b54642@freescale.com>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
[wsa: sorted includes]
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
index d4d8536..3ffdcf4 100644
--- a/drivers/i2c/busses/i2c-imx.c
+++ b/drivers/i2c/busses/i2c-imx.c
@@ -53,6 +53,7 @@
#include <linux/pinctrl/consumer.h>
#include <linux/platform_data/i2c-imx.h>
#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
#include <linux/sched.h>
#include <linux/slab.h>
@@ -120,6 +121,8 @@
#define I2CR_IEN_OPCODE_0 0x0
#define I2CR_IEN_OPCODE_1 I2CR_IEN
+#define I2C_PM_TIMEOUT 10 /* ms */
+
/** Variables ******************************************************************
*******************************************************************************/
@@ -527,9 +530,6 @@
i2c_imx_set_clk(i2c_imx);
- result = clk_prepare_enable(i2c_imx->clk);
- if (result)
- return result;
imx_i2c_write_reg(i2c_imx->ifdr, i2c_imx, IMX_I2C_IFDR);
/* Enable I2C controller */
imx_i2c_write_reg(i2c_imx->hwdata->i2sr_clr_opcode, i2c_imx, IMX_I2C_I2SR);
@@ -582,7 +582,6 @@
/* Disable I2C controller */
temp = i2c_imx->hwdata->i2cr_ien_opcode ^ I2CR_IEN,
imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
- clk_disable_unprepare(i2c_imx->clk);
}
static irqreturn_t i2c_imx_isr(int irq, void *dev_id)
@@ -901,6 +900,10 @@
dev_dbg(&i2c_imx->adapter.dev, "<%s>\n", __func__);
+ result = pm_runtime_get_sync(i2c_imx->adapter.dev.parent);
+ if (result < 0)
+ goto out;
+
/* Start I2C transfer */
result = i2c_imx_start(i2c_imx);
if (result) {
@@ -964,6 +967,10 @@
/* Stop I2C transfer */
i2c_imx_stop(i2c_imx);
+ pm_runtime_mark_last_busy(i2c_imx->adapter.dev.parent);
+ pm_runtime_put_autosuspend(i2c_imx->adapter.dev.parent);
+
+out:
dev_dbg(&i2c_imx->adapter.dev, "<%s> exit with: %s: %d\n", __func__,
(result < 0) ? "error" : "success msg",
(result < 0) ? result : num);
@@ -1083,7 +1090,7 @@
ret = clk_prepare_enable(i2c_imx->clk);
if (ret) {
- dev_err(&pdev->dev, "can't enable I2C clock\n");
+ dev_err(&pdev->dev, "can't enable I2C clock, ret=%d\n", ret);
return ret;
}
@@ -1107,6 +1114,18 @@
/* Set up adapter data */
i2c_set_adapdata(&i2c_imx->adapter, i2c_imx);
+ /* Set up platform driver data */
+ platform_set_drvdata(pdev, i2c_imx);
+
+ pm_runtime_set_autosuspend_delay(&pdev->dev, I2C_PM_TIMEOUT);
+ pm_runtime_use_autosuspend(&pdev->dev);
+ pm_runtime_set_active(&pdev->dev);
+ pm_runtime_enable(&pdev->dev);
+
+ ret = pm_runtime_get_sync(&pdev->dev);
+ if (ret < 0)
+ goto rpm_disable;
+
/* Set up clock divider */
i2c_imx->bitrate = IMX_I2C_BIT_RATE;
ret = of_property_read_u32(pdev->dev.of_node,
@@ -1125,12 +1144,11 @@
ret = i2c_add_numbered_adapter(&i2c_imx->adapter);
if (ret < 0) {
dev_err(&pdev->dev, "registration failed\n");
- goto clk_disable;
+ goto rpm_disable;
}
- /* Set up platform driver data */
- platform_set_drvdata(pdev, i2c_imx);
- clk_disable_unprepare(i2c_imx->clk);
+ pm_runtime_mark_last_busy(&pdev->dev);
+ pm_runtime_put_autosuspend(&pdev->dev);
dev_dbg(&i2c_imx->adapter.dev, "claimed irq %d\n", irq);
dev_dbg(&i2c_imx->adapter.dev, "device resources: %pR\n", res);
@@ -1143,6 +1161,12 @@
return 0; /* Return OK */
+rpm_disable:
+ pm_runtime_put_noidle(&pdev->dev);
+ pm_runtime_disable(&pdev->dev);
+ pm_runtime_set_suspended(&pdev->dev);
+ pm_runtime_dont_use_autosuspend(&pdev->dev);
+
clk_disable:
clk_disable_unprepare(i2c_imx->clk);
return ret;
@@ -1151,6 +1175,11 @@
static int i2c_imx_remove(struct platform_device *pdev)
{
struct imx_i2c_struct *i2c_imx = platform_get_drvdata(pdev);
+ int ret;
+
+ ret = pm_runtime_get_sync(&pdev->dev);
+ if (ret < 0)
+ return ret;
/* remove adapter */
dev_dbg(&i2c_imx->adapter.dev, "adapter removed\n");
@@ -1165,17 +1194,54 @@
imx_i2c_write_reg(0, i2c_imx, IMX_I2C_I2CR);
imx_i2c_write_reg(0, i2c_imx, IMX_I2C_I2SR);
+ clk_disable_unprepare(i2c_imx->clk);
+
+ pm_runtime_put_noidle(&pdev->dev);
+ pm_runtime_disable(&pdev->dev);
+
return 0;
}
+#ifdef CONFIG_PM
+static int i2c_imx_runtime_suspend(struct device *dev)
+{
+ struct imx_i2c_struct *i2c_imx = dev_get_drvdata(dev);
+
+ clk_disable_unprepare(i2c_imx->clk);
+
+ return 0;
+}
+
+static int i2c_imx_runtime_resume(struct device *dev)
+{
+ struct imx_i2c_struct *i2c_imx = dev_get_drvdata(dev);
+ int ret;
+
+ ret = clk_prepare_enable(i2c_imx->clk);
+ if (ret)
+ dev_err(dev, "can't enable I2C clock, ret=%d\n", ret);
+
+ return ret;
+}
+
+static const struct dev_pm_ops i2c_imx_pm_ops = {
+ SET_RUNTIME_PM_OPS(i2c_imx_runtime_suspend,
+ i2c_imx_runtime_resume, NULL)
+};
+#define I2C_IMX_PM_OPS (&i2c_imx_pm_ops)
+#else
+#define I2C_IMX_PM_OPS NULL
+#endif /* CONFIG_PM */
+
static struct platform_driver i2c_imx_driver = {
.probe = i2c_imx_probe,
.remove = i2c_imx_remove,
- .driver = {
- .name = DRIVER_NAME,
+ .driver = {
+ .name = DRIVER_NAME,
+ .pm = I2C_IMX_PM_OPS,
.of_match_table = i2c_imx_dt_ids,
},
- .id_table = imx_i2c_devtype,
+ .id_table = imx_i2c_devtype,
};
static int __init i2c_adap_imx_init(void)