[U-Boot] [PATCH 2/6 v2] i2c: designware_i2c: Add dw_i2c_enable() helper function

Stefan Roese
2016-03-23T05:46:24Z

dw_i2c_enable() is used to dis-/en-able the I2C controller. It makes
sense to add such a function, as the controller is dis-/en-abled
multiple times in the code. Additionally, this function now checks,
if the controller is really dis-/en-abled. This code is copied
from the Linux I2C driver version.

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Simon Glass <sjg@chromium.org>
Cc: Bin Meng <bmeng.cn@gmail.com>
Cc: Marek Vasut <marex@denx.de>
Cc: Heiko Schocher <hs@denx.de>
---
v2:
- Use true / false for binary values as suggested by Bin

drivers/i2c/designware_i2c.c | 46 +++++++++++++++++++++++++-------------------
1 file changed, 26 insertions(+), 20 deletions(-)

diff --git a/drivers/i2c/designware_i2c.c b/drivers/i2c/designware_i2c.c
index e768cde..2b0c8cb 100644
--- a/drivers/i2c/designware_i2c.c
+++ b/drivers/i2c/designware_i2c.c
@@ -34,6 +34,26 @@ static struct i2c_regs *i2c_get_base(struct i2c_adapter *adap)
return NULL;
}

+static void dw_i2c_enable(struct i2c_regs *i2c_base, bool enable)
+{
+ int timeout = 100;
+
+ do {
+ writel(enable, &i2c_base->ic_enable);
+ if ((readl(&i2c_base->ic_enable_status) & 1) == enable)
+ return;
+
+ /*
+ * Wait 10 times the signaling period of the highest I2C
+ * transfer supported by the driver (for 400KHz this is
+ * 25us) as described in the DesignWare I2C databook.
+ */
+ udelay(25);
+ } while (timeout--);
+
+ printf("timeout in %sabling I2C adapter\n", enable ? "en" : "dis");
+}
+
/*
* set_speed - Set the i2c speed mode (standard, high, fast)
* @i2c_spd: required i2c speed mode
@@ -45,12 +65,9 @@ static void set_speed(struct i2c_adapter *adap, int i2c_spd)
struct i2c_regs *i2c_base = i2c_get_base(adap);
unsigned int cntl;
unsigned int hcnt, lcnt;
- unsigned int enbl;

/* to set speed cltr must be disabled */
- enbl = readl(&i2c_base->ic_enable);
- enbl &= ~IC_ENABLE_0B;
- writel(enbl, &i2c_base->ic_enable);
+ dw_i2c_enable(i2c_base, false);

cntl = (readl(&i2c_base->ic_con) & (~IC_CON_SPD_MSK));

@@ -84,8 +101,7 @@ static void set_speed(struct i2c_adapter *adap, int i2c_spd)
writel(cntl, &i2c_base->ic_con);

/* Enable back i2c now speed set */
- enbl |= IC_ENABLE_0B;
- writel(enbl, &i2c_base->ic_enable);
+ dw_i2c_enable(i2c_base, true);
}

/*
@@ -123,12 +139,9 @@ static void dw_i2c_init(struct i2c_adapter *adap, int speed,
int slaveaddr)
{
struct i2c_regs *i2c_base = i2c_get_base(adap);
- unsigned int enbl;

/* Disable i2c */
- enbl = readl(&i2c_base->ic_enable);
- enbl &= ~IC_ENABLE_0B;
- writel(enbl, &i2c_base->ic_enable);
+ dw_i2c_enable(i2c_base, false);

writel((IC_CON_SD | IC_CON_SPD_FS | IC_CON_MM), &i2c_base->ic_con);
writel(IC_RX_TL, &i2c_base->ic_rx_tl);
@@ -138,9 +151,7 @@ static void dw_i2c_init(struct i2c_adapter *adap, int speed,
writel(slaveaddr, &i2c_base->ic_sar);

/* Enable i2c */
- enbl = readl(&i2c_base->ic_enable);
- enbl |= IC_ENABLE_0B;
- writel(enbl, &i2c_base->ic_enable);
+ dw_i2c_enable(i2c_base, true);
}

/*
@@ -152,19 +163,14 @@ static void dw_i2c_init(struct i2c_adapter *adap, int speed,
static void i2c_setaddress(struct i2c_adapter *adap, unsigned int i2c_addr)
{
struct i2c_regs *i2c_base = i2c_get_base(adap);
- unsigned int enbl;

/* Disable i2c */
- enbl = readl(&i2c_base->ic_enable);
- enbl &= ~IC_ENABLE_0B;
- writel(enbl, &i2c_base->ic_enable);
+ dw_i2c_enable(i2c_base, false);

writel(i2c_addr, &i2c_base->ic_tar);

/* Enable i2c */
- enbl = readl(&i2c_base->ic_enable);
- enbl |= IC_ENABLE_0B;
- writel(enbl, &i2c_base->ic_enable);
+ dw_i2c_enable(i2c_base, true);
}

/*
--
2.7.4