0005-support-for-dynamic-change-of-i2c-bus-clk-rate.patch

From ce6faaedef68204e8b132bf44a0e4d2432dfb7ad Mon Sep 17 00:00:00 2001
From: Arun-Prasad-V <arun.prasad.v@intel.com>
Date: Mon, 4 Nov 2024 12:52:39 +0530
Subject: [PATCH] Support for dynamic change of i2c bus-clk-rate

Signed-off-by: Arun Prasad V <arun.prasad.v@intel.com>
---
 drivers/i2c/busses/i2c-tegra.c | 42 +++++++++++++++++++++++++++++++
 drivers/i2c/i2c-core-base.c    | 45 ++++++++++++++++++++++++++++++++++
 include/linux/i2c.h            |  5 ++++
 3 files changed, 92 insertions(+)

diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
index cd50436e5734..4269343266c2 100644
--- a/drivers/i2c/busses/i2c-tegra.c
+++ b/drivers/i2c/busses/i2c-tegra.c
@@ -1484,6 +1484,37 @@ static int tegra_i2c_xfer_msg(struct tegra_i2c_dev *i2c_dev,
 	return 0;
 }
 
+static int tegra_i2c_change_clock_rate(struct tegra_i2c_dev *i2c_dev)
+{
+	u32 val;
+	int err;
+
+	val = I2C_CNFG_NEW_MASTER_FSM | I2C_CNFG_PACKET_MODE_EN |
+	      FIELD_PREP(I2C_CNFG_DEBOUNCE_CNT, 2);
+
+	if (i2c_dev->hw->has_multi_master_mode)
+		val |= I2C_CNFG_MULTI_MASTER_MODE;
+
+	i2c_writel(i2c_dev, val, I2C_CNFG);
+
+	if (i2c_dev->prod_list)
+		tegra_i2c_config_prod_settings(i2c_dev);
+	else
+		tegra_i2c_set_clk_params(i2c_dev);
+
+	err = tegra_i2c_set_div_clk(i2c_dev);
+	if (err) {
+		dev_err(i2c_dev->dev, "failed to set div-clk rate: %d\n", err);
+		return err;
+	}
+
+	err = tegra_i2c_wait_for_config_load(i2c_dev);
+	if (err)
+		return err;
+
+	return err;
+}
+
 static int tegra_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[],
 			  int num)
 {
@@ -1497,6 +1528,16 @@ static int tegra_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[],
 		return ret;
 	}
 
+	if (adap->bus_clk_rate != i2c_dev->bus_clk_rate) {
+		i2c_dev->bus_clk_rate = adap->bus_clk_rate;
+		 ret = tegra_i2c_change_clock_rate(i2c_dev);
+		 if (ret) {
+			 dev_err(i2c_dev->dev,
+					 "failed changing clock rate: %d\n", ret);
+			 return ret;
+		 }
+	}
+
 	for (i = 0; i < num; i++) {
 		enum msg_end_type end_type = MSG_END_STOP;
 
@@ -1957,6 +1998,7 @@ static int tegra_i2c_probe(struct platform_device *pdev)
 	i2c_dev->adapter.class = I2C_CLASS_DEPRECATED;
 	i2c_dev->adapter.algo = &tegra_i2c_algo;
 	i2c_dev->adapter.nr = pdev->id;
+	i2c_dev->adapter.bus_clk_rate = i2c_dev->bus_clk_rate;
 
 	if (i2c_dev->hw->supports_bus_clear)
 		i2c_dev->adapter.bus_recovery_info = &tegra_i2c_recovery_info;
diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
index c232535ca8f4..2edd24973cca 100644
--- a/drivers/i2c/i2c-core-base.c
+++ b/drivers/i2c/i2c-core-base.c
@@ -1285,10 +1285,33 @@ delete_device_store(struct device *dev, struct device_attribute *attr,
 static DEVICE_ATTR_IGNORE_LOCKDEP(delete_device, S_IWUSR, NULL,
 				  delete_device_store);
 
+static ssize_t show_bus_clk_rate(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct i2c_adapter *adap = to_i2c_adapter(dev);
+
+	return sprintf(buf, "%ld\n", adap->bus_clk_rate);
+}
+
+static ssize_t set_bus_clk_rate(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t count)
+{
+	struct i2c_adapter *adap = to_i2c_adapter(dev);
+	char *p = (char *)buf;
+	int bus_clk_rate;
+
+	bus_clk_rate = memparse(p, &p);
+	dev_info(dev, "Setting clock rate %d on next transfer\n", bus_clk_rate);
+	adap->bus_clk_rate = bus_clk_rate;
+	return count;
+}
+static DEVICE_ATTR(bus_clk_rate, 0644, show_bus_clk_rate, set_bus_clk_rate);
+
 static struct attribute *i2c_adapter_attrs[] = {
 	&dev_attr_name.attr,
 	&dev_attr_new_device.attr,
 	&dev_attr_delete_device.attr,
+	&dev_attr_bus_clk_rate.attr,
 	NULL
 };
 ATTRIBUTE_GROUPS(i2c_adapter);
@@ -1401,6 +1424,28 @@ static int i2c_setup_host_notify_irq_domain(struct i2c_adapter *adap)
 	return 0;
 }
 
+int i2c_set_adapter_bus_clk_rate(struct i2c_adapter *adap, int bus_rate)
+{
+	i2c_lock_bus(adap, I2C_LOCK_ROOT_ADAPTER);
+	adap->bus_clk_rate = bus_rate;
+	i2c_unlock_bus(adap, I2C_LOCK_ROOT_ADAPTER);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(i2c_set_adapter_bus_clk_rate);
+
+int i2c_get_adapter_bus_clk_rate(struct i2c_adapter *adap)
+{
+	int bus_clk_rate;
+
+	i2c_lock_bus(adap, I2C_LOCK_ROOT_ADAPTER);
+	bus_clk_rate = adap->bus_clk_rate;
+	i2c_unlock_bus(adap, I2C_LOCK_ROOT_ADAPTER);
+
+	return bus_clk_rate;
+}
+EXPORT_SYMBOL_GPL(i2c_get_adapter_bus_clk_rate);
+
 /**
  * i2c_handle_smbus_host_notify - Forward a Host Notify event to the correct
  * I2C client.
diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index 2ce3efbe9198..9d876ad6373c 100644
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -131,6 +131,10 @@ int i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num);
 /* Unlocked flavor */
 int __i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num);
 
+/* Change bus clock rate for i2c adapter */
+extern int i2c_set_adapter_bus_clk_rate(struct i2c_adapter *adap, int bus_rate);
+extern int i2c_get_adapter_bus_clk_rate(struct i2c_adapter *adap);
+
 /* This is the very generalized SMBus access routine. You probably do not
    want to use this, though; one of the functions below may be much easier,
    and probably just as fast.
@@ -737,6 +741,7 @@ struct i2c_adapter {
 	const struct i2c_adapter_quirks *quirks;
 
 	struct irq_domain *host_notify_domain;
+	unsigned long bus_clk_rate;
 	struct regulator *bus_regulator;
 
 	struct dentry *debugfs;
 #define to_i2c_adapter(d) container_of(d, struct i2c_adapter, dev)
-- 
2.34.1