[PATCH-v5 5/5] i2c: pxa: Add ILCR (tLow & tHigh) configuration support

[Vaibhav Hiremath <vaibhav.hiremath@linaro.org>]

With addition of PXA910 family of devices, the TWSI module supports
SCL clock adjustment using ILCR register.

This patch enables the control and configuration of ICLR through DT
properties,

i2c-sclk-high-time-ns:
  SCLK high time (tHigh), for standard/fast/high speed mode
i2c-sclk-low-time-ns:
  SCLK low time (tLow), for standard/fast/high speed mode

Note that in case of standard and fast mod, the tLow and tHigh counters
are same, and software will use tLow value.

Also, brought up devm_clk_get() fn above i2c_pxa_probe_dt(), as it
uses clk rate for timing calculations.

Signed-off-by: Vaibhav Hiremath <vaibhav.hiremath@linaro.org>
Signed-off-by: Jett.Zhou <jtzhou@marvell.com>
Signed-off-by: Yi Zhang <yizhang@marvell.com>
---
 drivers/i2c/busses/i2c-pxa.c | 69 ++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 63 insertions(+), 6 deletions(-)

diff --git a/drivers/i2c/busses/i2c-pxa.c b/drivers/i2c/busses/i2c-pxa.c
index 8d76197..6012ae5 100644
--- a/drivers/i2c/busses/i2c-pxa.c
+++ b/drivers/i2c/busses/i2c-pxa.c
@@ -195,6 +195,9 @@ struct pxa_i2c {
 	unsigned long		rate;
 	bool			highmode_enter;
 	bool			disable_after_xfer;
+
+	unsigned int		sclk_thigh_load_cnt;
+	unsigned int		sclk_tlow_load_cnt;
 };
 
 #define _IBMR(i2c)	((i2c)->reg_ibmr)
@@ -507,6 +510,36 @@ static void i2c_pxa_set_slave(struct pxa_i2c *i2c, int errcode)
 #define i2c_pxa_set_slave(i2c, err)	do { } while (0)
 #endif
 
+static void i2c_pxa_do_sclk_adj(struct pxa_i2c *i2c)
+{
+	unsigned int reg_ilcr;
+
+	if (!i2c->reg_ilcr)
+		return;
+
+	reg_ilcr = readl(_ILCR(i2c));
+
+	/* For standard/fast mode tlow and thigh counters are same */
+	if (i2c->sclk_tlow_load_cnt) {
+		unsigned int mask, shift;
+
+		mask = i2c->high_mode ? ILCR_HLVL_MASK :
+			i2c->fast_mode ? ILCR_FLV_MASK : ILCR_SLV_MASK;
+		shift = i2c->high_mode ? ILCR_HLVL_SHIFT :
+			i2c->fast_mode ? ILCR_FLV_SHIFT : ILCR_SLV_SHIFT;
+
+		reg_ilcr &= ~mask;
+		reg_ilcr |= i2c->sclk_tlow_load_cnt << shift;
+	}
+
+	if (i2c->high_mode && i2c->sclk_thigh_load_cnt) {
+		reg_ilcr &= ~ILCR_HLVH_MASK;
+		reg_ilcr |= i2c->sclk_thigh_load_cnt << ILCR_HLVH_SHIFT;
+	}
+
+	writel(reg_ilcr, _ILCR(i2c));
+}
+
 static void i2c_pxa_reset(struct pxa_i2c *i2c)
 {
 	pr_debug("Resetting I2C Controller Unit\n");
@@ -526,6 +559,8 @@ static void i2c_pxa_reset(struct pxa_i2c *i2c)
 	writel(I2C_ICR_INIT | (i2c->fast_mode ? ICR_FM : 0), _ICR(i2c));
 	writel(readl(_ICR(i2c)) | (i2c->high_mode ? ICR_HS : 0), _ICR(i2c));
 
+	i2c_pxa_do_sclk_adj(i2c);
+
 #ifdef CONFIG_I2C_PXA_SLAVE
 	dev_info(&i2c->adap.dev, "Enabling slave mode\n");
 	writel(readl(_ICR(i2c)) | ICR_SADIE | ICR_ALDIE | ICR_SSDIE, _ICR(i2c));
@@ -1198,6 +1233,26 @@ static int i2c_pxa_probe_dt(struct platform_device *pdev, struct pxa_i2c *i2c,
 
 	*i2c_types = (enum pxa_i2c_types)(of_id->data);
 
+	/* optional properties */
+	if (of_device_is_compatible(np, "mrvl,mmp-twsi")) {
+		unsigned int tlow = 0, thigh = 0;
+		unsigned int clk_ns;
+
+		/* clock time in nsec */
+		clk_ns = 1000000 / (i2c->rate / 1000);
+
+		of_property_read_u32(np, "i2c-sclk-high-time-ns", &thigh);
+		i2c->sclk_thigh_load_cnt = thigh / clk_ns;
+
+		of_property_read_u32(np, "i2c-sclk-low-time-ns", &tlow);
+		i2c->sclk_tlow_load_cnt = tlow / clk_ns;
+
+		/* For std/fast mode tlow & thigh have same bit-fields */
+		if (!i2c->high_mode &&
+			(i2c->sclk_tlow_load_cnt != i2c->sclk_thigh_load_cnt))
+			dev_warn(&i2c->adap.dev,
+				"mismatch of tLow & tHigh values, using tLow\n");
+	}
 	return 0;
 }
 
@@ -1248,6 +1303,14 @@ static int i2c_pxa_probe(struct platform_device *dev)
 		return irq;
 	}
 
+	i2c->clk = devm_clk_get(&dev->dev, NULL);
+	if (IS_ERR(i2c->clk)) {
+		dev_err(&dev->dev, "failed to get the clk: %ld\n", PTR_ERR(i2c->clk));
+		return PTR_ERR(i2c->clk);
+	}
+
+	i2c->rate = clk_get_rate(i2c->clk);
+
 	/* Default adapter num to device id; i2c_pxa_probe_dt can override. */
 	i2c->adap.nr = dev->id;
 
@@ -1265,12 +1328,6 @@ static int i2c_pxa_probe(struct platform_device *dev)
 
 	strlcpy(i2c->adap.name, "pxa_i2c-i2c", sizeof(i2c->adap.name));
 
-	i2c->clk = devm_clk_get(&dev->dev, NULL);
-	if (IS_ERR(i2c->clk)) {
-		dev_err(&dev->dev, "failed to get the clk: %ld\n", PTR_ERR(i2c->clk));
-		return PTR_ERR(i2c->clk);
-	}
-
 	i2c->reg_ibmr = i2c->reg_base + pxa_reg_layout[i2c_type].ibmr;
 	i2c->reg_idbr = i2c->reg_base + pxa_reg_layout[i2c_type].idbr;
 	i2c->reg_icr = i2c->reg_base + pxa_reg_layout[i2c_type].icr;
-- 
1.9.1