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Commit 36ecbcab authored by Shubhrajyoti Datta's avatar Shubhrajyoti Datta Committed by Wolfram Sang
Browse files

i2c: xiic: Implement power management 



Enable power management. This patch enables the clocks before transfer
and disables after the transfer. It also adds the clock description.

Signed-off-by: default avatarShubhrajyoti Datta <shubhraj@xilinx.com>
Acked-by: default avatarRob Herring <robh@kernel.org>
Signed-off-by: default avatarWolfram Sang <wsa@the-dreams.de>
parent 33f5ccc3

Documentation/devicetree/bindings/i2c/i2c-xiic.txt

+3 −0
Original line number Diff line number Diff line
@@ -6,14 +6,17 @@ Required properties: 
- interrupts : IIC controller unterrupt

- #address-cells = <1>

- #size-cells = <0>

- clocks: Input clock specifier. Refer to common clock bindings.



Optional properties:

- Child nodes conforming to i2c bus binding

- clock-names: Input clock name, should be 'pclk'.



Example:



	axi_iic_0: i2c@40800000 {

		compatible = "xlnx,xps-iic-2.00.a";

		clocks = <&clkc 15>;

		interrupts = < 1 2 >;

		reg = < 0x40800000 0x10000 >;

drivers/i2c/busses/i2c-xiic.c

+81 −7
Original line number Diff line number Diff line
@@ -37,6 +37,8 @@ 
#include <linux/io.h>

#include <linux/slab.h>

#include <linux/of.h>

#include <linux/clk.h>

#include <linux/pm_runtime.h>



#define DRIVER_NAME "xiic-i2c"
@@ -66,6 +68,7 @@ enum xiic_endian { 
 * @endianness: big/little-endian byte order

 */

struct xiic_i2c {

	struct device		*dev;

	void __iomem		*base;

	wait_queue_head_t	wait;

	struct i2c_adapter	adap;
@@ -77,6 +80,7 @@ struct xiic_i2c { 
	struct i2c_msg		*rx_msg;

	int			rx_pos;

	enum xiic_endian	endianness;

	struct clk *clk;

};
@@ -164,6 +168,7 @@ struct xiic_i2c { 


#define XIIC_RESET_MASK             0xAUL



#define XIIC_PM_TIMEOUT		1000	/* ms */

/*

 * The following constant is used for the device global interrupt enable

 * register, to enable all interrupts for the device, this is the only bit
@@ -676,9 +681,13 @@ static int xiic_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num) 
	dev_dbg(adap->dev.parent, "%s entry SR: 0x%x\n", __func__,

		xiic_getreg8(i2c, XIIC_SR_REG_OFFSET));



	err = pm_runtime_get_sync(i2c->dev);

	if (err < 0)

		return err;



	err = xiic_busy(i2c);

	if (err)

		return err;

		goto out;



	i2c->tx_msg = msgs;

	i2c->nmsgs = num;
@@ -686,14 +695,20 @@ static int xiic_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num) 
	xiic_start_xfer(i2c);



	if (wait_event_timeout(i2c->wait, (i2c->state == STATE_ERROR) ||

		(i2c->state == STATE_DONE), HZ))

		return (i2c->state == STATE_DONE) ? num : -EIO;

	else {

		(i2c->state == STATE_DONE), HZ)) {

		err = (i2c->state == STATE_DONE) ? num : -EIO;

		goto out;

	} else {

		i2c->tx_msg = NULL;

		i2c->rx_msg = NULL;

		i2c->nmsgs = 0;

		return -ETIMEDOUT;

		err = -ETIMEDOUT;

		goto out;

	}

out:

	pm_runtime_mark_last_busy(i2c->dev);

	pm_runtime_put_autosuspend(i2c->dev);

	return err;

}



static u32 xiic_func(struct i2c_adapter *adap)
@@ -748,13 +763,28 @@ static int xiic_i2c_probe(struct platform_device *pdev) 
	mutex_init(&i2c->lock);

	init_waitqueue_head(&i2c->wait);



	i2c->clk = devm_clk_get(&pdev->dev, NULL);

	if (IS_ERR(i2c->clk)) {

		dev_err(&pdev->dev, "input clock not found.\n");

		return PTR_ERR(i2c->clk);

	}

	ret = clk_prepare_enable(i2c->clk);

	if (ret) {

		dev_err(&pdev->dev, "Unable to enable clock.\n");

		return ret;

	}

	i2c->dev = &pdev->dev;

	pm_runtime_enable(i2c->dev);

	pm_runtime_set_autosuspend_delay(i2c->dev, XIIC_PM_TIMEOUT);

	pm_runtime_use_autosuspend(i2c->dev);

	pm_runtime_set_active(i2c->dev);

	ret = devm_request_threaded_irq(&pdev->dev, irq, xiic_isr,

					xiic_process, IRQF_ONESHOT,

					pdev->name, i2c);



	if (ret < 0) {

		dev_err(&pdev->dev, "Cannot claim IRQ\n");

		return ret;

		goto err_clk_dis;

	}



	/*
@@ -776,7 +806,7 @@ static int xiic_i2c_probe(struct platform_device *pdev) 
	if (ret) {

		dev_err(&pdev->dev, "Failed to add adapter\n");

		xiic_deinit(i2c);

		return ret;

		goto err_clk_dis;

	}



	if (pdata) {
@@ -786,16 +816,30 @@ static int xiic_i2c_probe(struct platform_device *pdev) 
	}



	return 0;



err_clk_dis:

	pm_runtime_set_suspended(&pdev->dev);

	pm_runtime_disable(&pdev->dev);

	clk_disable_unprepare(i2c->clk);

	return ret;

}



static int xiic_i2c_remove(struct platform_device *pdev)

{

	struct xiic_i2c *i2c = platform_get_drvdata(pdev);

	int ret;



	/* remove adapter & data */

	i2c_del_adapter(&i2c->adap);



	ret = clk_prepare_enable(i2c->clk);

	if (ret) {

		dev_err(&pdev->dev, "Unable to enable clock.\n");

		return ret;

	}

	xiic_deinit(i2c);

	clk_disable_unprepare(i2c->clk);

	pm_runtime_disable(&pdev->dev);



	return 0;

}
@@ -808,12 +852,42 @@ static const struct of_device_id xiic_of_match[] = { 
MODULE_DEVICE_TABLE(of, xiic_of_match);

#endif



static int __maybe_unused cdns_i2c_runtime_suspend(struct device *dev)

{

	struct platform_device *pdev = to_platform_device(dev);

	struct xiic_i2c *i2c = platform_get_drvdata(pdev);



	clk_disable(i2c->clk);



	return 0;

}



static int __maybe_unused cdns_i2c_runtime_resume(struct device *dev)

{

	struct platform_device *pdev = to_platform_device(dev);

	struct xiic_i2c *i2c = platform_get_drvdata(pdev);

	int ret;



	ret = clk_enable(i2c->clk);

	if (ret) {

		dev_err(dev, "Cannot enable clock.\n");

		return ret;

	}



	return 0;

}



static const struct dev_pm_ops xiic_dev_pm_ops = {

	SET_RUNTIME_PM_OPS(cdns_i2c_runtime_suspend,

			   cdns_i2c_runtime_resume, NULL)

};

static struct platform_driver xiic_i2c_driver = {

	.probe   = xiic_i2c_probe,

	.remove  = xiic_i2c_remove,

	.driver  = {

		.name = DRIVER_NAME,

		.of_match_table = of_match_ptr(xiic_of_match),

		.pm = &xiic_dev_pm_ops,

	},

};