[PATCH RFC] i2c: omap: Fix the revision register read

Shubhrajyoti D
2012-10-31T08:59:19Z

The revision register on OMAP4 is a 16-bit lo and a 16-bit
hi. Currently the driver reads only the lower 8-bits.
Fix the same by preventing the truncating of the rev register
for OMAP4.

Also use the scheme bit ie bit-14 of the hi register to know if it
is OMAP_I2C_IP_VERSION_2.

On platforms previous to OMAP4 the offset 0x04 is IE register whose
bit-14 reset value is 0, the code uses the same to its advantage.

The dev->regs is populated after reading the rev_hi. A NULL check
has been added in the resume handler to prevent the access before
the setting of the regs.

Signed-off-by: Shubhrajyoti D <shubhrajyoti-l0cyMroinI0@public.gmane.org>
---
todo: some of the flag checks can be removed in favour of revision check.

drivers/i2c/busses/i2c-omap.c | 35 +++++++++++++++++++++++++----------
1 files changed, 25 insertions(+), 10 deletions(-)

diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
index db31eae..651a7f7 100644
--- a/drivers/i2c/busses/i2c-omap.c
+++ b/drivers/i2c/busses/i2c-omap.c
@@ -51,7 +51,8 @@
/* I2C controller revisions present on specific hardware */
#define OMAP_I2C_REV_ON_2430 0x36
#define OMAP_I2C_REV_ON_3430_3530 0x3C
-#define OMAP_I2C_REV_ON_3630_4430 0x40
+#define OMAP_I2C_REV_ON_3630 0x40
+#define OMAP_I2C_REV_ON_4430_PLUS 0x5040

/* timeout waiting for the controller to respond */
#define OMAP_I2C_TIMEOUT (msecs_to_jiffies(1000))
@@ -202,7 +203,7 @@ struct omap_i2c_dev {
* fifo_size==0 implies no fifo
* if set, should be trsh+1
*/
- u8 rev;
+ u16 rev;
unsigned b_hw:1; /* bad h/w fixes */
unsigned receiver:1; /* true when we're in receiver mode */
u16 iestate; /* Saved interrupt register */
@@ -490,7 +491,7 @@ static void omap_i2c_resize_fifo(struct omap_i2c_dev *dev, u8 size, bool is_rx)

omap_i2c_write_reg(dev, OMAP_I2C_BUF_REG, buf);

- if (dev->rev < OMAP_I2C_REV_ON_3630_4430)
+ if (dev->rev < OMAP_I2C_REV_ON_3630)
dev->b_hw = 1; /* Enable hardware fixes */

/* calculate wakeup latency constraint for MPU */
@@ -1064,6 +1065,8 @@ omap_i2c_probe(struct platform_device *pdev)
const struct of_device_id *match;
int irq;
int r;
+ u16 rev_lo;
+ u16 rev_hi;

/* NOTE: driver uses the static register mapping */
mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
@@ -1117,11 +1120,6 @@ omap_i2c_probe(struct platform_device *pdev)

dev->reg_shift = (dev->flags >> OMAP_I2C_FLAG_BUS_SHIFT__SHIFT) & 3;

- if (dev->dtrev == OMAP_I2C_IP_VERSION_2)
- dev->regs = (u8 *)reg_map_ip_v2;
- else
- dev->regs = (u8 *)reg_map_ip_v1;
-
pm_runtime_enable(dev->dev);
pm_runtime_set_autosuspend_delay(dev->dev, OMAP_I2C_PM_TIMEOUT);
pm_runtime_use_autosuspend(dev->dev);
@@ -1130,7 +1128,21 @@ omap_i2c_probe(struct platform_device *pdev)
if (IS_ERR_VALUE(r))
goto err_free_mem;

- dev->rev = omap_i2c_read_reg(dev, OMAP_I2C_REV_REG) & 0xff;
+ /* Read the Rev hi bit-14 ie scheme this is 1 indicates ver2 or
+ * highlander.
+ * On omap3 Offset 4 is IE Reg the bit 14 is XDR_IE which is 0 at reset.
+ */
+ rev_hi = __raw_readw(dev->base + 0x04);
+
+ if (rev_hi & 0x4000) {/* If scheme 1*/
+ dev->regs = (u8 *)reg_map_ip_v2;
+ dev->rev = omap_i2c_read_reg(dev, OMAP_I2C_IP_V2_REVNB_HI);
+ rev_lo = omap_i2c_read_reg(dev, OMAP_I2C_IP_V2_REVNB_LO);
+ dev_info(dev->dev, "the low rev %x\n", rev_lo);
+ } else {
+ dev->regs = (u8 *)reg_map_ip_v1;
+ dev->rev = omap_i2c_read_reg(dev, OMAP_I2C_REV_REG) & 0xff;
+ }

dev->errata = 0;

@@ -1155,7 +1167,7 @@ omap_i2c_probe(struct platform_device *pdev)

dev->fifo_size = (dev->fifo_size / 2);

- if (dev->rev < OMAP_I2C_REV_ON_3630_4430)
+ if (dev->rev < OMAP_I2C_REV_ON_3630)
dev->b_hw = 1; /* Enable hardware fixes */

/* calculate wakeup latency constraint for MPU */
@@ -1264,6 +1276,9 @@ static int omap_i2c_runtime_resume(struct device *dev)
struct platform_device *pdev = to_platform_device(dev);
struct omap_i2c_dev *_dev = platform_get_drvdata(pdev);

+ if (!_dev->regs)
+ return 0;
+
if (_dev->flags & OMAP_I2C_FLAG_RESET_REGS_POSTIDLE) {
omap_i2c_write_reg(_dev, OMAP_I2C_CON_REG, 0);
omap_i2c_write_reg(_dev, OMAP_I2C_PSC_REG, _dev->pscstate);
--
1.7.5.4