linux-kernel - [PATCH] i2c: i2c-mux-gpio: Enable this driver in ACPI land

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Date:   Fri,  9 Oct 2020 15:43:20 -0700
From:   Evan Green <evgreen@...omium.org>
To:     Peter Rosin <peda@...ntia.se>
Cc:     Wolfram Sang <wsa@...nel.org>, Evan Green <evgreen@...omium.org>,
        Peter Korsgaard <peter.korsgaard@...co.com>,
        linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] i2c: i2c-mux-gpio: Enable this driver in ACPI land

Enable i2c-mux-gpio devices to be defined via ACPI. The idle-state
property translates directly to a fwnode_property_*() call. The child
reg property translates naturally into _ADR in ACPI.

The i2c-parent is a little trickier, since of's phandle definition
suggests the i2c mux could live in a completely different part of
the tree than its upstream i2c controller. For now in ACPI,
just assume that the i2c-mux-gpio device will always be a direct
child of the i2c controller. If the additional flexibility of
defining muxes in wildly different locations from their parent
controllers is required, it can be added later.

Signed-off-by: Evan Green <evgreen@...omium.org>
---

 drivers/i2c/muxes/i2c-mux-gpio.c | 77 +++++++++++++++++++++-----------
 1 file changed, 50 insertions(+), 27 deletions(-)

diff --git a/drivers/i2c/muxes/i2c-mux-gpio.c b/drivers/i2c/muxes/i2c-mux-gpio.c
index 4effe563e9e8d..f195e95e8a037 100644
--- a/drivers/i2c/muxes/i2c-mux-gpio.c
+++ b/drivers/i2c/muxes/i2c-mux-gpio.c
@@ -49,34 +49,46 @@ static int i2c_mux_gpio_deselect(struct i2c_mux_core *muxc, u32 chan)
 	return 0;
 }
 
-#ifdef CONFIG_OF
-static int i2c_mux_gpio_probe_dt(struct gpiomux *mux,
-					struct platform_device *pdev)
+static int i2c_mux_gpio_probe_fw(struct gpiomux *mux,
+				 struct platform_device *pdev)
 {
-	struct device_node *np = pdev->dev.of_node;
-	struct device_node *adapter_np, *child;
-	struct i2c_adapter *adapter;
+	struct device *dev = &pdev->dev;
+	struct device_node *np = dev->of_node;
+	acpi_handle dev_handle;
+	struct device_node *adapter_np;
+	struct i2c_adapter *adapter = NULL;
+	struct fwnode_handle *child = NULL;
 	unsigned *values;
 	int i = 0;
 
-	if (!np)
-		return -ENODEV;
+	if (is_of_node(dev->fwnode)) {
+		if (!np)
+			return -ENODEV;
 
-	adapter_np = of_parse_phandle(np, "i2c-parent", 0);
-	if (!adapter_np) {
-		dev_err(&pdev->dev, "Cannot parse i2c-parent\n");
-		return -ENODEV;
+		adapter_np = of_parse_phandle(np, "i2c-parent", 0);
+		if (!adapter_np) {
+			dev_err(&pdev->dev, "Cannot parse i2c-parent\n");
+			return -ENODEV;
+		}
+		adapter = of_find_i2c_adapter_by_node(adapter_np);
+		of_node_put(adapter_np);
+
+	} else if (is_acpi_node(dev->fwnode)) {
+		/*
+		 * In ACPI land the mux should be a direct child of the i2c
+		 * bus it muxes.
+		 */
+		dev_handle = ACPI_HANDLE(dev->parent);
+		adapter = i2c_acpi_find_adapter_by_handle(dev_handle);
 	}
-	adapter = of_find_i2c_adapter_by_node(adapter_np);
-	of_node_put(adapter_np);
+
 	if (!adapter)
 		return -EPROBE_DEFER;
 
 	mux->data.parent = i2c_adapter_id(adapter);
 	put_device(&adapter->dev);
 
-	mux->data.n_values = of_get_child_count(np);
-
+	mux->data.n_values = device_get_child_node_count(dev);
 	values = devm_kcalloc(&pdev->dev,
 			      mux->data.n_values, sizeof(*mux->data.values),
 			      GFP_KERNEL);
@@ -85,24 +97,35 @@ static int i2c_mux_gpio_probe_dt(struct gpiomux *mux,
 		return -ENOMEM;
 	}
 
-	for_each_child_of_node(np, child) {
-		of_property_read_u32(child, "reg", values + i);
+	device_for_each_child_node(dev, child) {
+		if (is_of_node(child)) {
+			fwnode_property_read_u32(child, "reg", values + i);
+
+		} else if (is_acpi_node(child)) {
+			unsigned long long adr;
+			acpi_status status;
+
+			status = acpi_evaluate_integer(ACPI_HANDLE_FWNODE(child),
+						       METHOD_NAME__ADR,
+						       NULL, &adr);
+			if (ACPI_SUCCESS(status)) {
+				*(values + i) = adr;
+
+			} else {
+				dev_err(dev, "Cannot get address");
+				return -EINVAL;
+			}
+		}
+
 		i++;
 	}
 	mux->data.values = values;
 
-	if (of_property_read_u32(np, "idle-state", &mux->data.idle))
+	if (fwnode_property_read_u32(dev->fwnode, "idle-state", &mux->data.idle))
 		mux->data.idle = I2C_MUX_GPIO_NO_IDLE;
 
 	return 0;
 }
-#else
-static int i2c_mux_gpio_probe_dt(struct gpiomux *mux,
-					struct platform_device *pdev)
-{
-	return 0;
-}
-#endif
 
 static int i2c_mux_gpio_probe(struct platform_device *pdev)
 {
@@ -118,7 +141,7 @@ static int i2c_mux_gpio_probe(struct platform_device *pdev)
 		return -ENOMEM;
 
 	if (!dev_get_platdata(&pdev->dev)) {
-		ret = i2c_mux_gpio_probe_dt(mux, pdev);
+		ret = i2c_mux_gpio_probe_fw(mux, pdev);
 		if (ret < 0)
 			return ret;
 	} else {
-- 
2.26.2