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Date: Wed, 25 May 2016 19:41:19 +0530
From: Ravikumar Kattekola <rk@...com>
To: <tony@...mide.com>, <wsa@...-dreams.de>,
<linux-omap@...r.kernel.org>, <linux-i2c@...r.kernel.org>,
<linux-kernel@...r.kernel.org>
Subject: [RFC 1/1] drivers: i2c: omap: Add slave support
I2C controller on most of the omap devices has both master and slave
capability but the i2c framework has been missing support for registering
a bus in slave mode for long.
Recently the i2c slave support has been added to i2c framework,
the following patch adds the required support for omap_i2c driver to
register a controller as a slave device and be deriven by
an external/internal master.
The slave interface requires us to add following mandatory events
1. I2C_SLAVE_WRITE_REQUESTED
2. I2C_SLAVE_READ_REQUESTED
3. I2C_SLAVE_WRITE_RECEIVED
4. I2C_SLAVE_READ_PROCESSED
and
5. I2C_SLAVE_STOP
The omap i2c controller (at least on dra7x devices)
doesn't have start/stop (STT/STP) support for slave mode
so event #5 is not implemented in the driver.
Signed-off-by: Ravikumar Kattekola <rk@...com>
---
drivers/i2c/busses/i2c-omap.c | 144 ++++++++++++++++++++++++++++++++++++++++++
1 file changed, 144 insertions(+)
diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
index ab1279b..ccfc49f 100644
--- a/drivers/i2c/busses/i2c-omap.c
+++ b/drivers/i2c/busses/i2c-omap.c
@@ -89,6 +89,7 @@ enum {
/* I2C Interrupt Enable Register (OMAP_I2C_IE): */
#define OMAP_I2C_IE_XDR (1 << 14) /* TX Buffer drain int enable */
#define OMAP_I2C_IE_RDR (1 << 13) /* RX Buffer drain int enable */
+#define OMAP_I2C_IE_AAS (1 << 9) /* Addressed as Slave int enable */
#define OMAP_I2C_IE_XRDY (1 << 4) /* TX data ready int enable */
#define OMAP_I2C_IE_RRDY (1 << 3) /* RX data ready int enable */
#define OMAP_I2C_IE_ARDY (1 << 2) /* Access ready int enable */
@@ -202,6 +203,7 @@ struct omap_i2c_dev {
u8 *regs;
size_t buf_len;
struct i2c_adapter adapter;
+ struct i2c_client *slave;
u8 threshold;
u8 fifo_size; /* use as flag and value
* fifo_size==0 implies no fifo
@@ -1003,6 +1005,62 @@ omap_i2c_isr(int irq, void *dev_id)
return ret;
}
+#ifdef CONFIG_I2C_SLAVE
+static int omap_i2c_slave_irq(struct omap_i2c_dev *omap)
+{
+ u16 stat_raw;
+ u16 stat;
+ u16 bits;
+ u8 value;
+
+ stat_raw = omap_i2c_read_reg(omap, OMAP_I2C_IP_V2_IRQSTATUS_RAW);
+ bits = omap_i2c_read_reg(omap, OMAP_I2C_IE_REG);
+ stat_raw &= bits;
+
+ if (stat_raw & OMAP_I2C_STAT_AAS) {
+ omap_i2c_ack_stat(omap, OMAP_I2C_STAT_AAS);
+ stat_raw &= ~OMAP_I2C_STAT_AAS;
+ }
+
+ /* Someone's just sayin Hi? okay bye..*/
+ if (!stat_raw)
+ goto out;
+
+ dev_dbg(omap->dev, "IRQ (ISR = 0x%04x)\n", stat_raw);
+
+ if (stat_raw & OMAP_I2C_STAT_RRDY)
+ i2c_slave_event(omap->slave, I2C_SLAVE_WRITE_REQUESTED, &value);
+
+ do {
+ bits = omap_i2c_read_reg(omap, OMAP_I2C_IE_REG);
+ stat = omap_i2c_read_reg(omap, OMAP_I2C_STAT_REG);
+ stat &= bits;
+
+ if (stat & OMAP_I2C_STAT_AAS)
+ omap_i2c_ack_stat(omap, OMAP_I2C_STAT_AAS);
+
+ if (stat & OMAP_I2C_STAT_RRDY) {
+ value = omap_i2c_read_reg(omap, OMAP_I2C_DATA_REG);
+ i2c_slave_event(omap->slave, I2C_SLAVE_WRITE_RECEIVED,
+ &value);
+ omap_i2c_ack_stat(omap, OMAP_I2C_STAT_RRDY);
+ }
+
+ if (stat & OMAP_I2C_STAT_XRDY) {
+ i2c_slave_event(omap->slave, I2C_SLAVE_READ_REQUESTED,
+ &value);
+ omap_i2c_write_reg(omap, OMAP_I2C_DATA_REG, value);
+ i2c_slave_event(omap->slave, I2C_SLAVE_READ_PROCESSED,
+ &value);
+ omap_i2c_ack_stat(omap, OMAP_I2C_STAT_XRDY);
+ }
+
+ } while (stat);
+out:
+ return 0;
+}
+#endif
+
static irqreturn_t
omap_i2c_isr_thread(int this_irq, void *dev_id)
{
@@ -1011,6 +1069,13 @@ omap_i2c_isr_thread(int this_irq, void *dev_id)
u16 stat;
int err = 0, count = 0;
+#ifdef CONFIG_I2C_SLAVE
+ if (omap->slave) {
+ /* If a slave is registered pass on the interrupt */
+ err = omap_i2c_slave_irq(omap);
+ goto out;
+ }
+#endif
do {
bits = omap_i2c_read_reg(omap, OMAP_I2C_IE_REG);
stat = omap_i2c_read_reg(omap, OMAP_I2C_STAT_REG);
@@ -1139,9 +1204,88 @@ out:
return IRQ_HANDLED;
}
+#ifdef CONFIG_I2C_SLAVE
+static int omap_i2c_reg_slave(struct i2c_client *slave)
+{
+ struct omap_i2c_dev *omap = i2c_get_adapdata(slave->adapter);
+ u16 reg;
+ int ret = 0;
+
+ dev_info(omap->dev, "Registering as a slave @ %x\n", slave->addr);
+
+ /* Already registered as a slave?
+ * XXX: OMAP I2c controller supports up to four
+ * different OA, can we register as four different
+ * slaves?
+ */
+ if (omap->slave)
+ return -EBUSY;
+
+ ret = pm_runtime_get_sync(omap->dev);
+ if (ret < 0)
+ return ret;
+
+ omap->slave = slave;
+
+ /* Write OA: So that master(s) can talk to us */
+ omap_i2c_write_reg(omap, OMAP_I2C_OA_REG, slave->addr);
+
+ /* Set / Switch to slave mode */
+ reg = omap_i2c_read_reg(omap, OMAP_I2C_CON_REG);
+ reg &= ~OMAP_I2C_CON_MST;
+ omap_i2c_write_reg(omap, OMAP_I2C_CON_REG, reg);
+
+ /* Clear status */
+ omap_i2c_write_reg(omap, OMAP_I2C_SYSS_REG, 0);
+
+ /* As of now, We dont need all interrupts be enabled */
+ omap->iestate = OMAP_I2C_IE_AAS | OMAP_I2C_IE_XRDY | OMAP_I2C_IE_RRDY;
+
+ /* Clear interrupt mask */
+ omap_i2c_write_reg(omap, OMAP_I2C_IP_V2_IRQENABLE_CLR, 0xffff);
+
+ dev_dbg(omap->dev, "omap->iestate 0x%04x\n", omap->iestate);
+
+ /* Enable necessary interrupts */
+ omap_i2c_write_reg(omap, OMAP_I2C_IE_REG, omap->iestate);
+
+ return 0;
+
+}
+
+static int omap_i2c_unreg_slave(struct i2c_client *slave)
+{
+ struct omap_i2c_dev *omap = i2c_get_adapdata(slave->adapter);
+ u16 reg;
+
+ WARN_ON(!omap->slave);
+ omap->slave = NULL;
+
+ /* Switch to master mode */
+ reg = omap_i2c_read_reg(omap, OMAP_I2C_CON_REG);
+ reg |= OMAP_I2C_CON_MST;
+ omap_i2c_write_reg(omap, OMAP_I2C_CON_REG, reg);
+
+ /* clear status */
+ omap_i2c_write_reg(omap, OMAP_I2C_SYSS_REG, 0);
+
+ /* Just to make sure re-init in master mode
+ * Should we do a reset here?
+ */
+ omap_i2c_init(omap);
+
+ pm_runtime_put(omap->dev);
+ return 0;
+}
+#endif
+
static const struct i2c_algorithm omap_i2c_algo = {
.master_xfer = omap_i2c_xfer,
.functionality = omap_i2c_func,
+#ifdef CONFIG_I2C_SLAVE
+ .reg_slave = omap_i2c_reg_slave,
+ .unreg_slave = omap_i2c_unreg_slave,
+#endif /* CONFIG_I2C_SLAVE */
};
#ifdef CONFIG_OF
--
2.8.2.396.g5fe494c
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