[PATCH linux dev-4.16 v2] i2c: muxes: pca9641: new driver
From: Ken Chen
Date: Tue Mar 20 2018 - 02:21:47 EST
Signed-off-by: Ken Chen <chen.kenyy@xxxxxxxxxxxx>
---
v1->v2
- Merged PCA9641 code into i2c-mux-pca9541.c
- Modified title
- Add PCA9641 detect function
---
drivers/i2c/muxes/i2c-mux-pca9541.c | 184 ++++++++++++++++++++++++++++++++++--
1 file changed, 174 insertions(+), 10 deletions(-)
diff --git a/drivers/i2c/muxes/i2c-mux-pca9541.c b/drivers/i2c/muxes/i2c-mux-pca9541.c
index 6a39ada..493f947 100644
--- a/drivers/i2c/muxes/i2c-mux-pca9541.c
+++ b/drivers/i2c/muxes/i2c-mux-pca9541.c
@@ -1,5 +1,5 @@
/*
- * I2C multiplexer driver for PCA9541 bus master selector
+ * I2C multiplexer driver for PCA9541/PCA9641 bus master selector
*
* Copyright (c) 2010 Ericsson AB.
*
@@ -26,8 +26,8 @@
#include <linux/slab.h>
/*
- * The PCA9541 is a bus master selector. It supports two I2C masters connected
- * to a single slave bus.
+ * The PCA9541/PCA9641 is a bus master selector. It supports two I2C masters
+ * connected to a single slave bus.
*
* Before each bus transaction, a master has to acquire bus ownership. After the
* transaction is complete, bus ownership has to be released. This fits well
@@ -58,11 +58,43 @@
#define PCA9541_ISTAT_MYTEST (1 << 6)
#define PCA9541_ISTAT_NMYTEST (1 << 7)
+#define PCA9641_ID 0x00
+#define PCA9641_ID_MAGIC 0x38
+
+#define PCA9641_CONTROL 0x01
+#define PCA9641_STATUS 0x02
+#define PCA9641_TIME 0x03
+
+#define PCA9641_CTL_LOCK_REQ BIT(0)
+#define PCA9641_CTL_LOCK_GRANT BIT(1)
+#define PCA9641_CTL_BUS_CONNECT BIT(2)
+#define PCA9641_CTL_BUS_INIT BIT(3)
+#define PCA9641_CTL_SMBUS_SWRST BIT(4)
+#define PCA9641_CTL_IDLE_TIMER_DIS BIT(5)
+#define PCA9641_CTL_SMBUS_DIS BIT(6)
+#define PCA9641_CTL_PRIORITY BIT(7)
+
+#define PCA9641_STS_OTHER_LOCK BIT(0)
+#define PCA9641_STS_BUS_INIT_FAIL BIT(1)
+#define PCA9641_STS_BUS_HUNG BIT(2)
+#define PCA9641_STS_MBOX_EMPTY BIT(3)
+#define PCA9641_STS_MBOX_FULL BIT(4)
+#define PCA9641_STS_TEST_INT BIT(5)
+#define PCA9641_STS_SCL_IO BIT(6)
+#define PCA9641_STS_SDA_IO BIT(7)
+
+#define PCA9641_RES_TIME 0x03
+
#define BUSON (PCA9541_CTL_BUSON | PCA9541_CTL_NBUSON)
#define MYBUS (PCA9541_CTL_MYBUS | PCA9541_CTL_NMYBUS)
#define mybus(x) (!((x) & MYBUS) || ((x) & MYBUS) == MYBUS)
#define busoff(x) (!((x) & BUSON) || ((x) & BUSON) == BUSON)
+#define BUSOFF(x, y) (!((x) & PCA9641_CTL_LOCK_GRANT) && \
+ !((y) & PCA9641_STS_OTHER_LOCK))
+#define other_lock(x) ((x) & PCA9641_STS_OTHER_LOCK)
+#define lock_grant(x) ((x) & PCA9641_CTL_LOCK_GRANT)
+
/* arbitration timeouts, in jiffies */
#define ARB_TIMEOUT (HZ / 8) /* 125 ms until forcing bus ownership */
#define ARB2_TIMEOUT (HZ / 4) /* 250 ms until acquisition failure */
@@ -79,6 +111,7 @@ struct pca9541 {
static const struct i2c_device_id pca9541_id[] = {
{"pca9541", 0},
+ {"pca9641", 1},
{}
};
@@ -87,6 +120,7 @@ MODULE_DEVICE_TABLE(i2c, pca9541_id);
#ifdef CONFIG_OF
static const struct of_device_id pca9541_of_match[] = {
{ .compatible = "nxp,pca9541" },
+ { .compatible = "nxp,pca9641" },
{}
};
MODULE_DEVICE_TABLE(of, pca9541_of_match);
@@ -328,6 +362,125 @@ static int pca9541_release_chan(struct i2c_mux_core *muxc, u32 chan)
}
/*
+ * Arbitration management functions
+ */
+static void pca9641_release_bus(struct i2c_client *client)
+{
+ pca9541_reg_write(client, PCA9641_CONTROL, 0);
+}
+
+/*
+ * Channel arbitration
+ *
+ * Return values:
+ * <0: error
+ * 0 : bus not acquired
+ * 1 : bus acquired
+ */
+static int pca9641_arbitrate(struct i2c_client *client)
+{
+ struct i2c_mux_core *muxc = i2c_get_clientdata(client);
+ struct pca9541 *data = i2c_mux_priv(muxc);
+ int reg_ctl, reg_sts;
+
+ reg_ctl = pca9541_reg_read(client, PCA9641_CONTROL);
+ if (reg_ctl < 0)
+ return reg_ctl;
+ reg_sts = pca9541_reg_read(client, PCA9641_STATUS);
+
+ if (BUSOFF(reg_ctl, reg_sts)) {
+ /*
+ * Bus is off. Request ownership or turn it on unless
+ * other master requested ownership.
+ */
+ reg_ctl |= PCA9641_CTL_LOCK_REQ;
+ pca9541_reg_write(client, PCA9641_CONTROL, reg_ctl);
+ reg_ctl = pca9541_reg_read(client, PCA9641_CONTROL);
+
+ if (lock_grant(reg_ctl)) {
+ /*
+ * Other master did not request ownership,
+ * or arbitration timeout expired. Take the bus.
+ */
+ reg_ctl |= PCA9641_CTL_BUS_CONNECT
+ | PCA9641_CTL_LOCK_REQ;
+ pca9541_reg_write(client, PCA9641_CONTROL, reg_ctl);
+ data->select_timeout = SELECT_DELAY_SHORT;
+
+ return 1;
+ } else {
+ /*
+ * Other master requested ownership.
+ * Set extra long timeout to give it time to acquire it.
+ */
+ data->select_timeout = SELECT_DELAY_LONG * 2;
+ }
+ } else if (lock_grant(reg_ctl)) {
+ /*
+ * Bus is on, and we own it. We are done with acquisition.
+ */
+ reg_ctl |= PCA9641_CTL_BUS_CONNECT | PCA9641_CTL_LOCK_REQ;
+ pca9541_reg_write(client, PCA9641_CONTROL, reg_ctl);
+
+ return 1;
+ } else if (other_lock(reg_sts)) {
+ /*
+ * Other master owns the bus.
+ * If arbitration timeout has expired, force ownership.
+ * Otherwise request it.
+ */
+ data->select_timeout = SELECT_DELAY_LONG;
+ reg_ctl |= PCA9641_CTL_LOCK_REQ;
+ pca9541_reg_write(client, PCA9641_CONTROL, reg_ctl);
+ }
+ return 0;
+}
+
+static int pca9641_select_chan(struct i2c_mux_core *muxc, u32 chan)
+{
+ struct pca9541 *data = i2c_mux_priv(muxc);
+ struct i2c_client *client = data->client;
+ int ret;
+ unsigned long timeout = jiffies + ARB2_TIMEOUT;
+ /* give up after this time */
+
+ data->arb_timeout = jiffies + ARB_TIMEOUT;
+ /* force bus ownership after this time */
+
+ do {
+ ret = pca9641_arbitrate(client);
+ if (ret)
+ return ret < 0 ? ret : 0;
+
+ if (data->select_timeout == SELECT_DELAY_SHORT)
+ udelay(data->select_timeout);
+ else
+ msleep(data->select_timeout / 1000);
+ } while (time_is_after_eq_jiffies(timeout));
+
+ return -ETIMEDOUT;
+}
+
+static int pca9641_release_chan(struct i2c_mux_core *muxc, u32 chan)
+{
+ struct pca9541 *data = i2c_mux_priv(muxc);
+ struct i2c_client *client = data->client;
+
+ pca9641_release_bus(client);
+ return 0;
+}
+
+static int pca9641_detect_id(struct i2c_client *client)
+{
+ int reg;
+
+ reg = pca9541_reg_read(client, PCA9641_ID);
+ if (reg == PCA9641_ID_MAGIC)
+ return 1;
+ else
+ return 0;
+}
+/*
* I2C init/probing/exit functions
*/
static int pca9541_probe(struct i2c_client *client,
@@ -339,34 +492,45 @@ static int pca9541_probe(struct i2c_client *client,
struct pca9541 *data;
int force;
int ret;
+ int detect_id;
if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_BYTE_DATA))
return -ENODEV;
+ detect_id = pca9641_detect_id(client);
/*
* I2C accesses are unprotected here.
* We have to lock the adapter before releasing the bus.
*/
- i2c_lock_adapter(adap);
- pca9541_release_bus(client);
- i2c_unlock_adapter(adap);
-
+ if (detect_id == 0) {
+ i2c_lock_adapter(adap);
+ pca9541_release_bus(client);
+ i2c_unlock_adapter(adap);
+ } else {
+ i2c_lock_adapter(adap);
+ pca9641_release_bus(client);
+ i2c_unlock_adapter(adap);
+ }
/* Create mux adapter */
force = 0;
if (pdata)
force = pdata->modes[0].adap_id;
- muxc = i2c_mux_alloc(adap, &client->dev, 1, sizeof(*data),
+ if (detect_id == 0) {
+ muxc = i2c_mux_alloc(adap, &client->dev, 1, sizeof(*data),
I2C_MUX_ARBITRATOR,
pca9541_select_chan, pca9541_release_chan);
+ } else {
+ muxc = i2c_mux_alloc(adap, &client->dev, 1, sizeof(*data),
+ I2C_MUX_ARBITRATOR,
+ pca9641_select_chan, pca9641_release_chan);
+ }
if (!muxc)
return -ENOMEM;
data = i2c_mux_priv(muxc);
data->client = client;
-
i2c_set_clientdata(client, muxc);
-
ret = i2c_mux_add_adapter(muxc, force, 0, 0);
if (ret)
return ret;
--
2.9.3