[v2,RESEND,5/8] i2c: exynos5: Add bus clock support

Commit Message

Sam Protsenko Dec. 4, 2021, 9:58 p.m. UTC

In new Exynos SoCs (like Exynos850) where HSI2C is implemented as a
part of USIv2 block, there are two clocks provided to HSI2C controller:
  - PCLK: bus clock (APB), provides access to register interface
  - IPCLK: operating IP-core clock; SCL is derived from this one

Both clocks have to be asserted for HSI2C to be functional in that case.

Add code to obtain and enable/disable PCLK in addition to already
handled operating clock. Make it optional though, as older Exynos SoC
variants only have one HSI2C clock.

Signed-off-by: Sam Protsenko <[e-mail]>
Reviewed-by: Krzysztof Kozlowski <[e-mail]>
Reviewed-by: Chanho Park <[e-mail]>
---
Changes in v2:
  - Added R-b tag by Krzysztof Kozlowski
  - Added R-b tag by Chanho Park

 drivers/i2c/busses/i2c-exynos5.c | 46 ++++++++++++++++++++++++++------
 1 file changed, 38 insertions(+), 8 deletions(-)

Comments

Wolfram Sang Dec. 9, 2021, 9:11 a.m. UTC | #1

On Sat, Dec 04, 2021 at 11:58:17PM +0200, Sam Protsenko wrote:
> In new Exynos SoCs (like Exynos850) where HSI2C is implemented as a
> part of USIv2 block, there are two clocks provided to HSI2C controller:
>   - PCLK: bus clock (APB), provides access to register interface
>   - IPCLK: operating IP-core clock; SCL is derived from this one
> 
> Both clocks have to be asserted for HSI2C to be functional in that case.
> 
> Add code to obtain and enable/disable PCLK in addition to already
> handled operating clock. Make it optional though, as older Exynos SoC
> variants only have one HSI2C clock.
> 
> Signed-off-by: Sam Protsenko <[e-mail]>
> Reviewed-by: Krzysztof Kozlowski <[e-mail]>
> Reviewed-by: Chanho Park <[e-mail]>

This one doesn't apply here? What tree is this based on?

Sam Protsenko Dec. 9, 2021, 2:07 p.m. UTC | #2

On Thu, 9 Dec 2021 at 11:11, Wolfram Sang <[e-mail]> wrote:
>
> On Sat, Dec 04, 2021 at 11:58:17PM +0200, Sam Protsenko wrote:
> > In new Exynos SoCs (like Exynos850) where HSI2C is implemented as a
> > part of USIv2 block, there are two clocks provided to HSI2C controller:
> >   - PCLK: bus clock (APB), provides access to register interface
> >   - IPCLK: operating IP-core clock; SCL is derived from this one
> >
> > Both clocks have to be asserted for HSI2C to be functional in that case.
> >
> > Add code to obtain and enable/disable PCLK in addition to already
> > handled operating clock. Make it optional though, as older Exynos SoC
> > variants only have one HSI2C clock.
> >
> > Signed-off-by: Sam Protsenko <[e-mail]>
> > Reviewed-by: Krzysztof Kozlowski <[e-mail]>
> > Reviewed-by: Chanho Park <[e-mail]>
>
> This one doesn't apply here? What tree is this based on?
>

Based on linux-next. Might got outdated, or maybe I had some debug
patches in my branch at the time. Anyway, I've sent v3 only for this
patch [1]. Can you please try to apply that one?

Thanks!

[1] https://lkml.org/lkml/2021/12/9/584

Patch

diff --git a/drivers/i2c/busses/i2c-exynos5.c b/drivers/i2c/busses/i2c-exynos5.c
index 5198e71e8dab..9cde5ecb9449 100644
--- a/drivers/i2c/busses/i2c-exynos5.c
+++ b/drivers/i2c/busses/i2c-exynos5.c
@@ -182,7 +182,8 @@  struct exynos5_i2c {
 	unsigned int		irq;
 
 	void __iomem		*regs;
-	struct clk		*clk;
+	struct clk		*clk;		/* operating clock */
+	struct clk		*pclk;		/* bus clock */
 	struct device		*dev;
 	int			state;
 
@@ -757,10 +758,14 @@  static int exynos5_i2c_xfer(struct i2c_adapter *adap,
 	struct exynos5_i2c *i2c = adap->algo_data;
 	int i, ret;
 
-	ret = clk_enable(i2c->clk);
+	ret = clk_enable(i2c->pclk);
 	if (ret)
 		return ret;
 
+	ret = clk_enable(i2c->clk);
+	if (ret)
+		goto err_pclk;
+
 	for (i = 0; i < num; ++i) {
 		ret = exynos5_i2c_xfer_msg(i2c, msgs + i, i + 1 == num);
 		if (ret)
@@ -768,6 +773,8 @@  static int exynos5_i2c_xfer(struct i2c_adapter *adap,
 	}
 
 	clk_disable(i2c->clk);
+err_pclk:
+	clk_disable(i2c->pclk);
 
 	return ret ?: num;
 }
@@ -807,10 +814,18 @@  static int exynos5_i2c_probe(struct platform_device *pdev)
 		return -ENOENT;
 	}
 
-	ret = clk_prepare_enable(i2c->clk);
+	i2c->pclk = devm_clk_get(&pdev->dev, "hsi2c_pclk");
+	if (IS_ERR(i2c->pclk))
+		i2c->pclk = NULL; /* pclk is optional */
+
+	ret = clk_prepare_enable(i2c->pclk);
 	if (ret)
 		return ret;
 
+	ret = clk_prepare_enable(i2c->clk);
+	if (ret)
+		goto err_pclk;
+
 	i2c->regs = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(i2c->regs)) {
 		ret = PTR_ERR(i2c->regs);
@@ -853,6 +868,7 @@  static int exynos5_i2c_probe(struct platform_device *pdev)
 	platform_set_drvdata(pdev, i2c);
 
 	clk_disable(i2c->clk);
+	clk_disable(i2c->pclk);
 
 	dev_info(&pdev->dev, "%s: HSI2C adapter\n", dev_name(&i2c->adap.dev));
 
@@ -860,6 +876,9 @@  static int exynos5_i2c_probe(struct platform_device *pdev)
 
  err_clk:
 	clk_disable_unprepare(i2c->clk);
+
+ err_pclk:
+	clk_disable_unprepare(i2c->pclk);
 	return ret;
 }
 
@@ -870,6 +889,7 @@  static int exynos5_i2c_remove(struct platform_device *pdev)
 	i2c_del_adapter(&i2c->adap);
 
 	clk_unprepare(i2c->clk);
+	clk_unprepare(i2c->pclk);
 
 	return 0;
 }
@@ -881,6 +901,7 @@  static int exynos5_i2c_suspend_noirq(struct device *dev)
 
 	i2c_mark_adapter_suspended(&i2c->adap);
 	clk_unprepare(i2c->clk);
+	clk_unprepare(i2c->pclk);
 
 	return 0;
 }
@@ -890,21 +911,30 @@  static int exynos5_i2c_resume_noirq(struct device *dev)
 	struct exynos5_i2c *i2c = dev_get_drvdata(dev);
 	int ret = 0;
 
-	ret = clk_prepare_enable(i2c->clk);
+	ret = clk_prepare_enable(i2c->pclk);
 	if (ret)
 		return ret;
 
+	ret = clk_prepare_enable(i2c->clk);
+	if (ret)
+		goto err_pclk;
+
 	ret = exynos5_hsi2c_clock_setup(i2c);
-	if (ret) {
-		clk_disable_unprepare(i2c->clk);
-		return ret;
-	}
+	if (ret)
+		goto err_clk;
 
 	exynos5_i2c_init(i2c);
 	clk_disable(i2c->clk);
+	clk_disable(i2c->pclk);
 	i2c_mark_adapter_resumed(&i2c->adap);
 
 	return 0;
+
+err_clk:
+	clk_disable_unprepare(i2c->clk);
+err_pclk:
+	clk_disable_unprepare(i2c->pclk);
+	return ret;
 }
 #endif