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Subject[PATCH v2 5/5] i2c: mux: pca9541: add support for PCA9641
Date
Heavily based on code from Ken Chen <chen.kenyy@inventec.com>.

Signed-off-by: Peter Rosin <peda@axentia.se>
---
drivers/i2c/muxes/Kconfig | 6 +-
drivers/i2c/muxes/i2c-mux-pca9541.c | 137 ++++++++++++++++++++++++++++++++++--
2 files changed, 136 insertions(+), 7 deletions(-)

diff --git a/drivers/i2c/muxes/Kconfig b/drivers/i2c/muxes/Kconfig
index 52a4a922e7e6..8532841de5db 100644
--- a/drivers/i2c/muxes/Kconfig
+++ b/drivers/i2c/muxes/Kconfig
@@ -55,10 +55,10 @@ config I2C_MUX_LTC4306
will be called i2c-mux-ltc4306.

config I2C_MUX_PCA9541
- tristate "NXP PCA9541 I2C Master Selector"
+ tristate "NXP PCA9541/PCA9641 I2C Master Selectors"
help
- If you say yes here you get support for the NXP PCA9541
- I2C Master Selector.
+ If you say yes here you get support for the NXP PCA9541/PCA9641
+ I2C Master Selectors.

This driver can also be built as a module. If so, the module
will be called i2c-mux-pca9541.
diff --git a/drivers/i2c/muxes/i2c-mux-pca9541.c b/drivers/i2c/muxes/i2c-mux-pca9541.c
index 5eb36e3223d5..5d4e0c92e978 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 selectors
*
* Copyright (c) 2010 Ericsson AB.
*
@@ -28,8 +28,8 @@
#include <linux/slab.h>

/*
- * The PCA9541 is a bus master selector. It supports two I2C masters connected
- * to a single slave bus.
+ * The PCA9541 and PCA9641 are bus master selector. They support 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
@@ -63,6 +63,33 @@
#define PCA9541_BUSON (PCA9541_CTL_BUSON | PCA9541_CTL_NBUSON)
#define PCA9541_MYBUS (PCA9541_CTL_MYBUS | PCA9541_CTL_NMYBUS)

+#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
+
/* 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 */
@@ -73,6 +100,7 @@

enum chip_name {
pca9541,
+ pca9641,
};

struct chip_desc {
@@ -102,6 +130,21 @@ static bool pca9541_busoff(int ctl)
return (ctl & PCA9541_BUSON) == PCA9541_BUSON;
}

+static bool pca9641_lock_grant(int ctl)
+{
+ return !!(ctl & PCA9641_CTL_LOCK_GRANT);
+}
+
+static bool pca9641_other_lock(int sts)
+{
+ return !!(sts & PCA9641_STS_OTHER_LOCK);
+}
+
+static bool pca9641_busoff(int ctl, int sts)
+{
+ return !pca9641_lock_grant(ctl) && !pca9641_other_lock(sts);
+}
+
/*
* Write to chip register. Don't use i2c_transfer()/i2c_smbus_xfer()
* as they will try to lock the adapter a second time.
@@ -256,6 +299,86 @@ static int pca9541_arbitrate(struct i2c_client *client)
return 0;
}

+/* Release bus. */
+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 (pca9641_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 (pca9641_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;
+ }
+
+ /*
+ * Other master requested ownership.
+ * Set extra long timeout to give it time to acquire it.
+ */
+ data->select_timeout = SELECT_DELAY_LONG * 2;
+
+ return 0;
+ }
+
+ if (pca9641_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;
+ }
+
+ if (pca9641_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 pca9541_select_chan(struct i2c_mux_core *muxc, u32 chan)
{
struct pca9541 *data = i2c_mux_priv(muxc);
@@ -295,10 +418,15 @@ static const struct chip_desc chips[] = {
.arbitrate = pca9541_arbitrate,
.release_bus = pca9541_release_bus,
},
+ [pca9641] = {
+ .arbitrate = pca9641_arbitrate,
+ .release_bus = pca9641_release_bus,
+ },
};

static const struct i2c_device_id pca9541_id[] = {
{ "pca9541", pca9541 },
+ { "pca9641", pca9641 },
{}
};

@@ -307,6 +435,7 @@ MODULE_DEVICE_TABLE(i2c, pca9541_id);
#ifdef CONFIG_OF
static const struct of_device_id pca9541_of_match[] = {
{ .compatible = "nxp,pca9541", .data = &chips[pca9541] },
+ { .compatible = "nxp,pca9641", .data = &chips[pca9641] },
{}
};
MODULE_DEVICE_TABLE(of, pca9541_of_match);
@@ -392,5 +521,5 @@ static struct i2c_driver pca9541_driver = {
module_i2c_driver(pca9541_driver);

MODULE_AUTHOR("Guenter Roeck <linux@roeck-us.net>");
-MODULE_DESCRIPTION("PCA9541 I2C master selector driver");
+MODULE_DESCRIPTION("PCA9541/PCA9641 I2C master selector driver");
MODULE_LICENSE("GPL v2");
--
2.11.0
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