summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorLudovic Desroches <ludovic.desroches@atmel.com>2015-12-03 10:53:50 +0100
committerWolfram Sang <wsa@the-dreams.de>2015-12-03 21:42:37 +0100
commitcc018e3612e4a8244790521e88f9b1b7eb60dab0 (patch)
tree1a6221825ed4168ade4f7b0c42538c49c34ff276
parentd7a4c7633629c983a226ea3e32824360521c09b3 (diff)
i2c: at91: add support for the HOLD field
The hold field allows to configure the data hold time which can be set with the help of the generic binding 'i2c-sda-hold-time-ns'. This feature has been introduced with SAMA5D4 SoC family. Signed-off-by: Ludovic Desroches <ludovic.desroches@atmel.com> Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com> Acked-by: Rob Herring <robh@kernel.org> Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
-rw-r--r--Documentation/devicetree/bindings/i2c/i2c-at91.txt5
-rw-r--r--drivers/i2c/busses/i2c-at91.c53
2 files changed, 54 insertions, 4 deletions
diff --git a/Documentation/devicetree/bindings/i2c/i2c-at91.txt b/Documentation/devicetree/bindings/i2c/i2c-at91.txt
index 6e81dc153f3b..ef973a0343c7 100644
--- a/Documentation/devicetree/bindings/i2c/i2c-at91.txt
+++ b/Documentation/devicetree/bindings/i2c/i2c-at91.txt
@@ -3,7 +3,7 @@ I2C for Atmel platforms
Required properties :
- compatible : Must be "atmel,at91rm9200-i2c", "atmel,at91sam9261-i2c",
"atmel,at91sam9260-i2c", "atmel,at91sam9g20-i2c", "atmel,at91sam9g10-i2c",
- "atmel,at91sam9x5-i2c" or "atmel,sama5d2-i2c"
+ "atmel,at91sam9x5-i2c", "atmel,sama5d4-i2c" or "atmel,sama5d2-i2c"
- reg: physical base address of the controller and length of memory mapped
region.
- interrupts: interrupt number to the cpu.
@@ -17,6 +17,8 @@ Optional properties:
- dma-names: should contain "tx" and "rx".
- atmel,fifo-size: maximum number of data the RX and TX FIFOs can store for FIFO
capable I2C controllers.
+- i2c-sda-hold-time-ns: TWD hold time, only available for "atmel,sama5d4-i2c"
+ and "atmel,sama5d2-i2c".
- Child nodes conforming to i2c bus binding
Examples :
@@ -52,6 +54,7 @@ i2c0: i2c@f8034600 {
#size-cells = <0>;
clocks = <&flx0>;
atmel,fifo-size = <16>;
+ i2c-sda-hold-time-ns = <336>;
wm8731: wm8731@1a {
compatible = "wm8731";
diff --git a/drivers/i2c/busses/i2c-at91.c b/drivers/i2c/busses/i2c-at91.c
index 10835d1f559b..921d32bfcda8 100644
--- a/drivers/i2c/busses/i2c-at91.c
+++ b/drivers/i2c/busses/i2c-at91.c
@@ -64,6 +64,8 @@
#define AT91_TWI_IADR 0x000c /* Internal Address Register */
#define AT91_TWI_CWGR 0x0010 /* Clock Waveform Generator Reg */
+#define AT91_TWI_CWGR_HOLD_MAX 0x1f
+#define AT91_TWI_CWGR_HOLD(x) (((x) & AT91_TWI_CWGR_HOLD_MAX) << 24)
#define AT91_TWI_SR 0x0020 /* Status Register */
#define AT91_TWI_TXCOMP BIT(0) /* Transmission Complete */
@@ -110,6 +112,7 @@ struct at91_twi_pdata {
unsigned clk_offset;
bool has_unre_flag;
bool has_alt_cmd;
+ bool has_hold_field;
struct at_dma_slave dma_slave;
};
@@ -187,10 +190,11 @@ static void at91_init_twi_bus(struct at91_twi_dev *dev)
*/
static void at91_calc_twi_clock(struct at91_twi_dev *dev, int twi_clk)
{
- int ckdiv, cdiv, div;
+ int ckdiv, cdiv, div, hold = 0;
struct at91_twi_pdata *pdata = dev->pdata;
int offset = pdata->clk_offset;
int max_ckdiv = pdata->clk_max_div;
+ u32 twd_hold_time_ns = 0;
div = max(0, (int)DIV_ROUND_UP(clk_get_rate(dev->clk),
2 * twi_clk) - offset);
@@ -204,8 +208,33 @@ static void at91_calc_twi_clock(struct at91_twi_dev *dev, int twi_clk)
cdiv = 255;
}
- dev->twi_cwgr_reg = (ckdiv << 16) | (cdiv << 8) | cdiv;
- dev_dbg(dev->dev, "cdiv %d ckdiv %d\n", cdiv, ckdiv);
+ if (pdata->has_hold_field) {
+ of_property_read_u32(dev->dev->of_node, "i2c-sda-hold-time-ns",
+ &twd_hold_time_ns);
+
+ /*
+ * hold time = HOLD + 3 x T_peripheral_clock
+ * Use clk rate in kHz to prevent overflows when computing
+ * hold.
+ */
+ hold = DIV_ROUND_UP(twd_hold_time_ns
+ * (clk_get_rate(dev->clk) / 1000), 1000000);
+ hold -= 3;
+ if (hold < 0)
+ hold = 0;
+ if (hold > AT91_TWI_CWGR_HOLD_MAX) {
+ dev_warn(dev->dev,
+ "HOLD field set to its maximum value (%d instead of %d)\n",
+ AT91_TWI_CWGR_HOLD_MAX, hold);
+ hold = AT91_TWI_CWGR_HOLD_MAX;
+ }
+ }
+
+ dev->twi_cwgr_reg = (ckdiv << 16) | (cdiv << 8) | cdiv
+ | AT91_TWI_CWGR_HOLD(hold);
+
+ dev_dbg(dev->dev, "cdiv %d ckdiv %d hold %d (%d ns)\n",
+ cdiv, ckdiv, hold, twd_hold_time_ns);
}
static void at91_twi_dma_cleanup(struct at91_twi_dev *dev)
@@ -797,6 +826,7 @@ static struct at91_twi_pdata at91rm9200_config = {
.clk_offset = 3,
.has_unre_flag = true,
.has_alt_cmd = false,
+ .has_hold_field = false,
};
static struct at91_twi_pdata at91sam9261_config = {
@@ -804,6 +834,7 @@ static struct at91_twi_pdata at91sam9261_config = {
.clk_offset = 4,
.has_unre_flag = false,
.has_alt_cmd = false,
+ .has_hold_field = false,
};
static struct at91_twi_pdata at91sam9260_config = {
@@ -811,6 +842,7 @@ static struct at91_twi_pdata at91sam9260_config = {
.clk_offset = 4,
.has_unre_flag = false,
.has_alt_cmd = false,
+ .has_hold_field = false,
};
static struct at91_twi_pdata at91sam9g20_config = {
@@ -818,6 +850,7 @@ static struct at91_twi_pdata at91sam9g20_config = {
.clk_offset = 4,
.has_unre_flag = false,
.has_alt_cmd = false,
+ .has_hold_field = false,
};
static struct at91_twi_pdata at91sam9g10_config = {
@@ -825,6 +858,7 @@ static struct at91_twi_pdata at91sam9g10_config = {
.clk_offset = 4,
.has_unre_flag = false,
.has_alt_cmd = false,
+ .has_hold_field = false,
};
static const struct platform_device_id at91_twi_devtypes[] = {
@@ -854,6 +888,15 @@ static struct at91_twi_pdata at91sam9x5_config = {
.clk_offset = 4,
.has_unre_flag = false,
.has_alt_cmd = false,
+ .has_hold_field = false,
+};
+
+static struct at91_twi_pdata sama5d4_config = {
+ .clk_max_div = 7,
+ .clk_offset = 4,
+ .has_unre_flag = false,
+ .has_alt_cmd = false,
+ .has_hold_field = true,
};
static struct at91_twi_pdata sama5d2_config = {
@@ -861,6 +904,7 @@ static struct at91_twi_pdata sama5d2_config = {
.clk_offset = 4,
.has_unre_flag = true,
.has_alt_cmd = true,
+ .has_hold_field = true,
};
static const struct of_device_id atmel_twi_dt_ids[] = {
@@ -883,6 +927,9 @@ static const struct of_device_id atmel_twi_dt_ids[] = {
.compatible = "atmel,at91sam9x5-i2c",
.data = &at91sam9x5_config,
}, {
+ .compatible = "atmel,sama5d4-i2c",
+ .data = &sama5d4_config,
+ }, {
.compatible = "atmel,sama5d2-i2c",
.data = &sama5d2_config,
}, {