To enter high speed mode, following steps should be done:
1. When running in high speed mode, i2c clock rate is different
from standard mode. Clock rate must be set according to
specification first.
2. When i2c controller sends a master code and wins arbitration,
high speed mode is entered.
If you want to enable high speed mode, the following members of
platform data should be set to proper value:
1. "high_mode" should be set to "1".
2. "master_code" should be set to "8'b 0000_1xxx"(x is 0 or 1).
If no master_code is set, set to default value 0xe.
3. "rate" should be set according to specification.
Signed-off-by: Leilei Shang <shangll@xxxxxxxxxxx>
---
drivers/i2c/busses/i2c-pxa.c | 64 +++++++++++++++++++++++++++++++++++++++++-
include/linux/i2c/pxa-i2c.h | 3 ++
2 files changed, 66 insertions(+), 1 deletions(-)
diff --git a/drivers/i2c/busses/i2c-pxa.c b/drivers/i2c/busses/i2c-pxa.c
index ea6d45d..164324c 100644
--- a/drivers/i2c/busses/i2c-pxa.c
+++ b/drivers/i2c/busses/i2c-pxa.c
@@ -110,6 +110,8 @@ MODULE_DEVICE_TABLE(platform, i2c_pxa_id_table);
#define ICR_SADIE (1 << 13) /* slave address detected int enable */
#define ICR_UR (1 << 14) /* unit reset */
#define ICR_FM (1 << 15) /* fast mode */
+#define ICR_HS (1 << 16) /* High Speed mode */
+#define ICR_GPIOEN (1 << 19) /* enable GPIO mode for SCL in HS */
#define ISR_RWM (1 << 0) /* read/write mode */
#define ISR_ACKNAK (1 << 1) /* ack/nak status */
@@ -155,6 +157,10 @@ struct pxa_i2c {
int irq;
unsigned int use_pio :1;
unsigned int fast_mode :1;
+ unsigned int high_mode:1;
+ unsigned char master_code;
+ unsigned long rate;
+ bool highmode_enter;
};
#define _IBMR(i2c) ((i2c)->reg_ibmr)
@@ -459,6 +465,7 @@ static void i2c_pxa_reset(struct pxa_i2c *i2c)
/* set control register values */
writel(I2C_ICR_INIT | (i2c->fast_mode ? ICR_FM : 0), _ICR(i2c));
+ writel(readl(_ICR(i2c)) | (i2c->high_mode ? ICR_HS : 0), _ICR(i2c));
#ifdef CONFIG_I2C_PXA_SLAVE
dev_info(&i2c->adap.dev, "Enabling slave mode\n");
@@ -680,6 +687,34 @@ static int i2c_pxa_pio_set_master(struct pxa_i2c *i2c)
return 0;
}
+/*
+ * PXA I2C send master code
+ * 1. Load master code to IDBR and send it.
+ * Note for HS mode, set ICR [GPIOEN].
+ * 2. Wait until win arbitration.
+ */
+static int i2c_pxa_send_mastercode(struct pxa_i2c *i2c)
+{
+ u32 icr;
+ long timeout;
+
+ spin_lock_irq(&i2c->lock);
+ i2c->highmode_enter = true;
+ writel(i2c->master_code, _IDBR(i2c));
+
+ icr = readl(_ICR(i2c)) & ~(ICR_STOP | ICR_ALDIE);
+ icr |= ICR_GPIOEN | ICR_START | ICR_TB | ICR_ITEIE;
+ writel(icr, _ICR(i2c));
+
+ spin_unlock_irq(&i2c->lock);
+ timeout = wait_event_timeout(i2c->wait,
+ i2c->highmode_enter == false, HZ * 1);
+
+ i2c->highmode_enter = false;
+
+ return (timeout == 0) ? I2C_RETRY : 0;
+}
+
static int i2c_pxa_do_pio_xfer(struct pxa_i2c *i2c,
struct i2c_msg *msg, int num)
{
@@ -743,6 +778,14 @@ static int i2c_pxa_do_xfer(struct pxa_i2c *i2c, struct i2c_msg *msg, int num)
goto out;
}
+ if (i2c->high_mode) {
+ ret = i2c_pxa_send_mastercode(i2c);
+ if (ret) {
+ dev_err(&i2c->adap.dev, "i2c_pxa_send_mastercode timeout\n");
+ goto out;
+ }
+ }
+
spin_lock_irq(&i2c->lock);
i2c->msg = msg;
@@ -990,11 +1033,14 @@ static irqreturn_t i2c_pxa_handler(int this_irq, void *dev_id)
i2c_pxa_slave_txempty(i2c, isr);
if (isr & ISR_IRF)
i2c_pxa_slave_rxfull(i2c, isr);
- } else if (i2c->msg) {
+ } else if (i2c->msg && (!i2c->highmode_enter)) {
if (isr & ISR_ITE)
i2c_pxa_irq_txempty(i2c, isr);
if (isr & ISR_IRF)
i2c_pxa_irq_rxfull(i2c, isr);
+ } else if ((isr & ISR_ITE) && i2c->highmode_enter) {
+ i2c->highmode_enter = false;
+ wake_up(&i2c->wait);
} else {
i2c_pxa_scream_blue_murder(i2c, "spurious irq");
}
@@ -1079,6 +1125,11 @@ static int i2c_pxa_probe_pdata(struct platform_device *pdev,
if (plat) {
i2c->use_pio = plat->use_pio;
i2c->fast_mode = plat->fast_mode;
+ i2c->high_mode = plat->high_mode;
+ i2c->master_code = plat->master_code;
+ if (!i2c->master_code)
+ i2c->master_code = 0xe;
+ i2c->rate = plat->rate;
}
return 0;
}
@@ -1151,6 +1202,7 @@ static int i2c_pxa_probe(struct platform_device *dev)
i2c->irq = irq;
i2c->slave_addr = I2C_PXA_SLAVE_ADDR;
+ i2c->highmode_enter = false;
if (plat) {
#ifdef CONFIG_I2C_PXA_SLAVE
@@ -1160,6 +1212,16 @@ static int i2c_pxa_probe(struct platform_device *dev)
i2c->adap.class = plat->class;
}
+ if (i2c->high_mode) {
+ if (i2c->rate) {
+ clk_set_rate(i2c->clk, i2c->rate);
+ pr_info("i2c: <%s> set rate to %ld\n",
+ i2c->adap.name, clk_get_rate(i2c->clk));
+ } else
+ pr_warn("i2c: <%s> clock rate not set\n",
+ i2c->adap.name);
+ }
+
clk_enable(i2c->clk);
if (i2c->use_pio) {
diff --git a/include/linux/i2c/pxa-i2c.h b/include/linux/i2c/pxa-i2c.h
index 1a9f65e..53aab24 100644
--- a/include/linux/i2c/pxa-i2c.h
+++ b/include/linux/i2c/pxa-i2c.h
@@ -67,6 +67,9 @@ struct i2c_pxa_platform_data {
unsigned int class;
unsigned int use_pio :1;
unsigned int fast_mode :1;
+ unsigned int high_mode:1;
+ unsigned char master_code;
+ unsigned long rate;
};
extern void pxa_set_i2c_info(struct i2c_pxa_platform_data *info);
--
1.7.4.1
--
To unsubscribe from this list: send the line "unsubscribe linux-i2c" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
