i2c: pxa: migrate to new i2c_slave APIs

The i2c subsystem was enhanced circa 2015 to support operating as
an i2c-slave device.  Prior to that, the i2c-pxa driver supported
an i2c-slave but had its own APIs.  There are no existing in-kernel
drivers or platforms that utilize the i2c-pxa APIs.

Migrate the i2c-pxa driver to the general i2c-slave APIs so that
existing drivers, such as the i2c-slave-eeprom, can be used.

This has been tested with a Marvell EspressoBin, using i2c-pxa and
i2c-slave-eeprom, acting as a slave, and a RaspeberryPi 3, using the
at24 driver, acting as a master.

Signed-off-by: Patrick Williams <alpawi@amazon.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index 89cb8d7..45ca099 100644 (file)
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -875,6 +875,7 @@ config I2C_PXA_PCI
 config I2C_PXA_SLAVE
        bool "Intel PXA2XX I2C Slave comms support"
        depends on I2C_PXA && !X86_32
+       select I2C_SLAVE
        help
          Support I2C slave mode communications on the PXA I2C bus.  This
          is necessary for systems where the PXA may be a target on the

diff --git a/drivers/i2c/busses/i2c-pxa.c b/drivers/i2c/busses/i2c-pxa.c
index 2c3c3d6..c811646 100644 (file)
--- a/drivers/i2c/busses/i2c-pxa.c
+++ b/drivers/i2c/busses/i2c-pxa.c
@@ -180,7 +180,7 @@ struct pxa_i2c {
        struct i2c_adapter      adap;
        struct clk              *clk;
 #ifdef CONFIG_I2C_PXA_SLAVE
-       struct i2c_slave_client *slave;
+       struct i2c_client       *slave;
 #endif
 
        unsigned int            irqlogidx;
@@ -544,22 +544,23 @@ static void i2c_pxa_slave_txempty(struct pxa_i2c *i2c, u32 isr)
        if (isr & ISR_BED) {
                /* what should we do here? */
        } else {
-               int ret = 0;
+               u8 byte = 0;
 
                if (i2c->slave != NULL)
-                       ret = i2c->slave->read(i2c->slave->data);
+                       i2c_slave_event(i2c->slave, I2C_SLAVE_READ_PROCESSED,
+                                       &byte);
 
-               writel(ret, _IDBR(i2c));
+               writel(byte, _IDBR(i2c));
                writel(readl(_ICR(i2c)) | ICR_TB, _ICR(i2c));   /* allow next byte */
        }
 }
 
 static void i2c_pxa_slave_rxfull(struct pxa_i2c *i2c, u32 isr)
 {
-       unsigned int byte = readl(_IDBR(i2c));
+       u8 byte = readl(_IDBR(i2c));
 
        if (i2c->slave != NULL)
-               i2c->slave->write(i2c->slave->data, byte);
+               i2c_slave_event(i2c->slave, I2C_SLAVE_WRITE_RECEIVED, &byte);
 
        writel(readl(_ICR(i2c)) | ICR_TB, _ICR(i2c));
 }
@@ -572,9 +573,18 @@ static void i2c_pxa_slave_start(struct pxa_i2c *i2c, u32 isr)
                dev_dbg(&i2c->adap.dev, "SAD, mode is slave-%cx\n",
                       (isr & ISR_RWM) ? 'r' : 't');
 
-       if (i2c->slave != NULL)
-               i2c->slave->event(i2c->slave->data,
-                                (isr & ISR_RWM) ? I2C_SLAVE_EVENT_START_READ : I2C_SLAVE_EVENT_START_WRITE);
+       if (i2c->slave != NULL) {
+               if (isr & ISR_RWM) {
+                       u8 byte = 0;
+
+                       i2c_slave_event(i2c->slave, I2C_SLAVE_READ_REQUESTED,
+                                       &byte);
+                       writel(byte, _IDBR(i2c));
+               } else {
+                       i2c_slave_event(i2c->slave, I2C_SLAVE_WRITE_REQUESTED,
+                                       NULL);
+               }
+       }
 
        /*
         * slave could interrupt in the middle of us generating a
@@ -607,7 +617,7 @@ static void i2c_pxa_slave_stop(struct pxa_i2c *i2c)
                dev_dbg(&i2c->adap.dev, "ISR: SSD (Slave Stop)\n");
 
        if (i2c->slave != NULL)
-               i2c->slave->event(i2c->slave->data, I2C_SLAVE_EVENT_STOP);
+               i2c_slave_event(i2c->slave, I2C_SLAVE_STOP, NULL);
 
        if (i2c_debug > 2)
                dev_dbg(&i2c->adap.dev, "ISR: SSD (Slave Stop) acked\n");
@@ -619,6 +629,38 @@ static void i2c_pxa_slave_stop(struct pxa_i2c *i2c)
        if (i2c->msg)
                i2c_pxa_master_complete(i2c, I2C_RETRY);
 }
+
+static int i2c_pxa_slave_reg(struct i2c_client *slave)
+{
+       struct pxa_i2c *i2c = slave->adapter->algo_data;
+
+       if (i2c->slave)
+               return -EBUSY;
+
+       if (!i2c->reg_isar)
+               return -EAFNOSUPPORT;
+
+       i2c->slave = slave;
+       i2c->slave_addr = slave->addr;
+
+       writel(i2c->slave_addr, _ISAR(i2c));
+
+       return 0;
+}
+
+static int i2c_pxa_slave_unreg(struct i2c_client *slave)
+{
+       struct pxa_i2c *i2c = slave->adapter->algo_data;
+
+       WARN_ON(!i2c->slave);
+
+       i2c->slave_addr = I2C_PXA_SLAVE_ADDR;
+       writel(i2c->slave_addr, _ISAR(i2c));
+
+       i2c->slave = NULL;
+
+       return 0;
+}
 #else
 static void i2c_pxa_slave_txempty(struct pxa_i2c *i2c, u32 isr)
 {
@@ -1141,11 +1183,19 @@ static u32 i2c_pxa_functionality(struct i2c_adapter *adap)
 static const struct i2c_algorithm i2c_pxa_algorithm = {
        .master_xfer    = i2c_pxa_xfer,
        .functionality  = i2c_pxa_functionality,
+#ifdef CONFIG_I2C_PXA_SLAVE
+       .reg_slave      = i2c_pxa_slave_reg,
+       .unreg_slave    = i2c_pxa_slave_unreg,
+#endif
 };
 
 static const struct i2c_algorithm i2c_pxa_pio_algorithm = {
        .master_xfer    = i2c_pxa_pio_xfer,
        .functionality  = i2c_pxa_functionality,
+#ifdef CONFIG_I2C_PXA_SLAVE
+       .reg_slave      = i2c_pxa_slave_reg,
+       .unreg_slave    = i2c_pxa_slave_unreg,
+#endif
 };
 
 static const struct of_device_id i2c_pxa_dt_ids[] = {
@@ -1270,10 +1320,6 @@ static int i2c_pxa_probe(struct platform_device *dev)
        i2c->highmode_enter = false;
 
        if (plat) {
-#ifdef CONFIG_I2C_PXA_SLAVE
-               i2c->slave_addr = plat->slave_addr;
-               i2c->slave = plat->slave;
-#endif
                i2c->adap.class = plat->class;
        }