[PATCH 5/6] i2c: exynos5: Add bus clock support

Sam Protsenko
2021-12-01T19:05:28Z

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 <semen.protsenko@linaro.org>
---
drivers/i2c/busses/i2c-exynos5.c | 46 ++++++++++++++++++++++++++------
1 file changed, 38 insertions(+), 8 deletions(-)

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

--
2.30.2