[RFC PATCH] WIP: i2c: rcar: add HostNotify support

Wolfram Sang
2020-07-01T08:09:18Z

The I2C core can now utilize a slave interface to handle SMBus
HostNotify events. Enable it in this driver.

Not-yet-Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
---

Alain, this is the code needed to enable SMBus HostNotify for the
Renesas R-Car driver already using the binding we discussed yesterday.
I got it to work finally, so we have now two working cases. Good!

I do have some more review comments. I will send them out hopefully
later, but for sure somewhen today.

Thanks for working on it!

drivers/i2c/busses/i2c-rcar.c | 31 ++++++++++++++++++++++++++++---
1 file changed, 28 insertions(+), 3 deletions(-)

diff --git a/drivers/i2c/busses/i2c-rcar.c b/drivers/i2c/busses/i2c-rcar.c
index 19e89ab73b6f..9bc23d72ccae 100644
--- a/drivers/i2c/busses/i2c-rcar.c
+++ b/drivers/i2c/busses/i2c-rcar.c
@@ -20,6 +20,7 @@
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/i2c.h>
+#include <linux/i2c-smbus.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of_device.h>
@@ -105,10 +106,11 @@
#define ID_ARBLOST (1 << 3)
#define ID_NACK (1 << 4)
/* persistent flags */
+#define ID_P_HOST_NOTIFY BIT(28)
#define ID_P_REP_AFTER_RD BIT(29)
#define ID_P_NO_RXDMA BIT(30) /* HW forbids RXDMA sometimes */
#define ID_P_PM_BLOCKED BIT(31)
-#define ID_P_MASK GENMASK(31, 29)
+#define ID_P_MASK GENMASK(31, 28)

enum rcar_i2c_type {
I2C_RCAR_GEN1,
@@ -140,6 +142,8 @@ struct rcar_i2c_priv {

struct reset_control *rstc;
int irq;
+
+ struct i2c_client *host_client;
};

#define rcar_i2c_priv_to_dev(p) ((p)->adap.dev.parent)
@@ -881,14 +885,21 @@ static int rcar_unreg_slave(struct i2c_client *slave)

static u32 rcar_i2c_func(struct i2c_adapter *adap)
{
+ struct rcar_i2c_priv *priv = i2c_get_adapdata(adap);
+
/*
* This HW can't do:
* I2C_SMBUS_QUICK (setting FSB during START didn't work)
* I2C_M_NOSTART (automatically sends address after START)
* I2C_M_IGNORE_NAK (automatically sends STOP after NAK)
*/
- return I2C_FUNC_I2C | I2C_FUNC_SLAVE |
- (I2C_FUNC_SMBUS_EMUL & ~I2C_FUNC_SMBUS_QUICK);
+ u32 func = I2C_FUNC_I2C | I2C_FUNC_SLAVE |
+ (I2C_FUNC_SMBUS_EMUL & ~I2C_FUNC_SMBUS_QUICK);
+
+ if (priv->flags & ID_P_HOST_NOTIFY)
+ func |= I2C_FUNC_SMBUS_HOST_NOTIFY;
+
+ return func;
}

static const struct i2c_algorithm rcar_i2c_algo = {
@@ -986,6 +997,8 @@ static int rcar_i2c_probe(struct platform_device *pdev)
else
pm_runtime_put(dev);

+ if (of_property_read_bool(dev->of_node, "enable-host-notify"))
+ priv->flags |= ID_P_HOST_NOTIFY;

priv->irq = platform_get_irq(pdev, 0);
ret = devm_request_irq(dev, priv->irq, rcar_i2c_irq, 0, dev_name(dev), priv);
@@ -1000,10 +1013,20 @@ static int rcar_i2c_probe(struct platform_device *pdev)
if (ret < 0)
goto out_pm_disable;

+ if (priv->flags & ID_P_HOST_NOTIFY) {
+ priv->host_client = i2c_new_smbus_host_notify_device(adap);
+ if (IS_ERR(priv->host_client)) {
+ ret = PTR_ERR(priv->host_client);
+ goto out_del_device;
+ }
+ }
+
dev_info(dev, "probed\n");

return 0;

+ out_del_device:
+ i2c_del_adapter(&priv->adap);
out_pm_put:
pm_runtime_put(dev);
out_pm_disable:
@@ -1017,6 +1040,8 @@ static int rcar_i2c_remove(struct platform_device *pdev)
struct device *dev = &pdev->dev;

i2c_del_adapter(&priv->adap);
+ if (priv->host_client)
+ i2c_free_smbus_host_notify_device(priv->host_client);
rcar_i2c_release_dma(priv);
if (priv->flags & ID_P_PM_BLOCKED)
pm_runtime_put(dev);
--
2.20.1