i2c: do not enable fall back to Host Notify by default

Falling back unconditionally to HostNotify as primary client's interrupt
breaks some drivers which alter their functionality depending on whether
interrupt is present or not, so let's introduce a board flag telling I2C
core explicitly if we want wired interrupt or HostNotify-based one:
I2C_CLIENT_HOST_NOTIFY.

For DT-based systems we introduce "host-notify" property that we convert
to I2C_CLIENT_HOST_NOTIFY board flag.

Tested-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Acked-by: Pali Rohár <pali.rohar@gmail.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

diff --git a/Documentation/devicetree/bindings/i2c/i2c.txt b/Documentation/devicetree/bindings/i2c/i2c.txt
index 5fa691e6f6388320acd4199995ef0072e9e70faa..cee9d5055fa27c7593f5a9da09661c4f7eed9647 100644 (file)
--- a/Documentation/devicetree/bindings/i2c/i2c.txt
+++ b/Documentation/devicetree/bindings/i2c/i2c.txt
@@ -62,6 +62,9 @@ wants to support one of the below features, it should adapt the bindings below.
        "irq" and "wakeup" names are recognized by I2C core, other names are
        left to individual drivers.
 
+- host-notify
+       device uses SMBus host notify protocol instead of interrupt line.
+
 - multi-master
        states that there is another master active on this bus. The OS can use
        this information to adapt power management to keep the arbitration awake
@@ -81,6 +84,11 @@ Binding may contain optional "interrupts" property, describing interrupts
 used by the device. I2C core will assign "irq" interrupt (or the very first
 interrupt if not using interrupt names) as primary interrupt for the slave.
 
+Alternatively, devices supporting SMbus Host Notify, and connected to
+adapters that support this feature, may use "host-notify" property. I2C
+core will create a virtual interrupt for Host Notify and assign it as
+primary interrupt for the slave.
+
 Also, if device is marked as a wakeup source, I2C core will set up "wakeup"
 interrupt for the device. If "wakeup" interrupt name is not present in the
 binding, then primary interrupt will be used as wakeup interrupt.

diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index cf9e396d7702c6c769e2106a6938f90c6ddbb7a9..7b117240f1ea4a6cbb9f25dbdbf7cfb140bb4a85 100644 (file)
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -931,7 +931,10 @@ static int i2c_device_probe(struct device *dev)
        if (!client->irq) {
                int irq = -ENOENT;
 
-               if (dev->of_node) {
+               if (client->flags & I2C_CLIENT_HOST_NOTIFY) {
+                       dev_dbg(dev, "Using Host Notify IRQ\n");
+                       irq = i2c_smbus_host_notify_to_irq(client);
+               } else if (dev->of_node) {
                        irq = of_irq_get_byname(dev->of_node, "irq");
                        if (irq == -EINVAL || irq == -ENODATA)
                                irq = of_irq_get(dev->of_node, 0);
@@ -940,14 +943,7 @@ static int i2c_device_probe(struct device *dev)
                }
                if (irq == -EPROBE_DEFER)
                        return irq;
-               /*
-                * ACPI and OF did not find any useful IRQ, try to see
-                * if Host Notify can be used.
-                */
-               if (irq < 0) {
-                       dev_dbg(dev, "Using Host Notify IRQ\n");
-                       irq = i2c_smbus_host_notify_to_irq(client);
-               }
+
                if (irq < 0)
                        irq = 0;
 
@@ -1716,6 +1712,9 @@ static struct i2c_client *of_i2c_register_device(struct i2c_adapter *adap,
        info.of_node = of_node_get(node);
        info.archdata = &dev_ad;
 
+       if (of_property_read_bool(node, "host-notify"))
+               info.flags |= I2C_CLIENT_HOST_NOTIFY;
+
        if (of_get_property(node, "wakeup-source", NULL))
                info.flags |= I2C_CLIENT_WAKE;
 

diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index b2109c522dec0726d6e6e390358a79be4bcdf891..4b45ec46161fd66d6e7fd32f53dd71b8ac1cab42 100644 (file)
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -665,6 +665,7 @@ i2c_unlock_adapter(struct i2c_adapter *adapter)
 #define I2C_CLIENT_TEN         0x10    /* we have a ten bit chip address */
                                        /* Must equal I2C_M_TEN below */
 #define I2C_CLIENT_SLAVE       0x20    /* we are the slave */
+#define I2C_CLIENT_HOST_NOTIFY 0x40    /* We want to use I2C host notify */
 #define I2C_CLIENT_WAKE                0x80    /* for board_info; true iff can wake */
 #define I2C_CLIENT_SCCB                0x9000  /* Use Omnivision SCCB protocol */
                                        /* Must match I2C_M_STOP|IGNORE_NAK */