Re: [PATCH 1/2 v3] i2c: exynos5: add support for HSI2C on Exynos5260 SoC

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Hi Naveen,

On 06.02.2014 13:06, Naveen Krishna Chatradhi wrote:
This patch implements a variant struct to handle the differences
(like fifo_depths) in the HSI2C modules across SoCs.

Adds a new compatible to support HSI2C module on Exynos5260.
Also resets the module as an init sequence (Needed by Exynos5260).

Signed-off-by: Naveen Krishna Chatradhi <ch.naveen@xxxxxxxxxxx>
---
Changes since v2:
1. Used variant struct as suggested by Tomasz Figa.
2. Change compatible strings from samsung,exynos5-hsi2c to
    samsung,exynos5250-hsi2c based on the first SoC to see the feature.
3. Using reset as init sequences.
4. Merged the 2 patches into one.

  .../devicetree/bindings/i2c/i2c-exynos5.txt        |    8 ++-
  drivers/i2c/busses/i2c-exynos5.c                   |   64 ++++++++++++++++----
  2 files changed, 58 insertions(+), 14 deletions(-)

diff --git a/Documentation/devicetree/bindings/i2c/i2c-exynos5.txt b/Documentation/devicetree/bindings/i2c/i2c-exynos5.txt
index 056732c..5bc4998 100644
--- a/Documentation/devicetree/bindings/i2c/i2c-exynos5.txt
+++ b/Documentation/devicetree/bindings/i2c/i2c-exynos5.txt
@@ -5,7 +5,11 @@ at various speeds ranging from 100khz to 3.4Mhz.

  Required properties:
    - compatible: value should be.
-      -> "samsung,exynos5-hsi2c", for i2c compatible with exynos5 hsi2c.

Device tree bindings need to be backwards compatible, so you need to keep this compatible string supported, just marked as (DEPRECATED).

Driver-wise, it will use the same driver data / variant struct as "samsung,exynos5250-hsi2c", just one more entry in OF match table is needed.

+	-> "samsung,exynos5250-hsi2c", for i2c compatible with HSI2C available
+				on Exynos5250 and Exynos5420 SoCs.
+	-> "samsung,exynos5260-hsi2c", for i2c compatible with HSI2C available
+				on Exynos5260 SoCs.
+
    - reg: physical base address of the controller and length of memory mapped
      region.
    - interrupts: interrupt number to the cpu.
@@ -26,7 +30,7 @@ Optional properties:
  Example:

  hsi2c@12ca0000 {
-	compatible = "samsung,exynos5-hsi2c";
+	compatible = "samsung,exynos5250-hsi2c";
  	reg = <0x12ca0000 0x100>;
  	interrupts = <56>;
  	clock-frequency = <100000>;

[snip]

@@ -483,6 +514,7 @@ static void exynos5_i2c_message_start(struct exynos5_i2c *i2c, int stop)
  	u32 i2c_auto_conf = 0;
  	u32 fifo_ctl;
  	unsigned long flags;
+	unsigned short trig_lvl;

  	i2c_ctl = readl(i2c->regs + HSI2C_CTL);
  	i2c_ctl &= ~(HSI2C_TXCHON | HSI2C_RXCHON);
@@ -493,13 +525,19 @@ static void exynos5_i2c_message_start(struct exynos5_i2c *i2c, int stop)

  		i2c_auto_conf = HSI2C_READ_WRITE;

-		fifo_ctl |= HSI2C_RXFIFO_TRIGGER_LEVEL(HSI2C_DEF_TXFIFO_LVL);
+		trig_lvl = (i2c->msg->len > i2c->variant->fifo_depth) ?
+			(i2c->variant->fifo_depth * 3/4) : i2c->msg->len;
+		fifo_ctl |= HSI2C_RXFIFO_TRIGGER_LEVEL(trig_lvl);
+

This is a rather serious semantic change, that doesn't look to belong to this patch. If this is needed, it should be done in a separate patch.

  		int_en |= (HSI2C_INT_RX_ALMOSTFULL_EN |
  			HSI2C_INT_TRAILING_EN);
  	} else {
  		i2c_ctl |= HSI2C_TXCHON;

-		fifo_ctl |= HSI2C_TXFIFO_TRIGGER_LEVEL(HSI2C_DEF_RXFIFO_LVL);
+		trig_lvl = (i2c->msg->len > i2c->variant->fifo_depth) ?
+			(i2c->variant->fifo_depth * 1/4) : i2c->msg->len;
+		fifo_ctl |= HSI2C_TXFIFO_TRIGGER_LEVEL(trig_lvl);
+

Ditto.

Best regards,
Tomasz
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