Re: [PATCH v4 00/13] Add ACPI _DSD and unified device properties support

From: David Woodhouse <dwmw2@infradead.org>
To: Mark Rutland <mark.rutland@arm.com>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Mika Westerberg <mika.westerberg@linux.intel.com>,
	ACPI Devel Maling List <linux-acpi@vger.kernel.org>,
	Aaron Lu <aaron.lu@intel.com>,
	"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	Linus Walleij <linus.walleij@linaro.org>,
	Alexandre Courbot <gnurou@gmail.com>,
	Dmitry Torokhov <dmitry.torokhov@gmail.com>,
	Bryan Wu <cooloney@gmail.com>,
	"grant.likely@linaro.org" <grant.likely@linaro.org>,
	Arnd Bergmann <arnd@arndb.de>,
	Darren Hart <dvhart@linux.intel.com>
Subject: Re: [PATCH v4 00/13] Add ACPI _DSD and unified device properties support
Date: Wed, 14 Jan 2015 10:42:23 -0800	[thread overview]
Message-ID: <1421260943.14516.19.camel@infradead.org> (raw)
In-Reply-To: <20141015131551.GC20034@leverpostej>


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I'm looking again at updating of_serial to work with ACPI properties. 

Specifically, I want to support a serial port with a non-standard baud
rate, something like this:

    Device(COM1) {
        Name(_HID, EisaId("PNP0501"))
        Name(_CID, EisaId("PRP0001"))
	Name(_DSD, Package() {
	    ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
            Package () {
		Package () {"compatible", Package () {"ns16550a"}},
		Package () {"clock-frequency", 2457600},
	    }
	})
        ...
    }

Firstly, the of_serial driver doesn't even get *invoked* unless I do
this:

diff --git a/drivers/acpi/property.c b/drivers/acpi/property.c
index 0d08373..eb1201a 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -2083,6 +2086,8 @@ static int acpi_add_single_object(struct acpi_device **child,
 	ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Added %s [%s] parent %s\n",
 		dev_name(&device->dev), (char *) buffer.pointer,
 		device->parent ? dev_name(&device->parent->dev) : "(null)"));
+	if (device->data.of_compatible)
+		acpi_create_platform_device(device);
 	kfree(buffer.pointer);
 	*child = device;
 	return 0;

Now it doesn't work because it uses of_match_device() to look the device
up and find the corresponding *data* for that entry in its match table.
And without CONFIG_OF, I don't *have* of_match_device().

We've talked about the fact that the platform bus probe function doesn't
pass you the match ID. Is that something we could potentially fix now
that things are a little more unified?

Or do we expect drivers still to have to use something like
of_match_id() to do the lookup again for themselves... and in that case
should we make of_match_id() available or produce a new
device_match_id() that they are expected to switch to?

-- 
dwmw2


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diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
index c79b43c..65cf850 100644
--- a/drivers/tty/serial/Kconfig
+++ b/drivers/tty/serial/Kconfig
@@ -1114,14 +1114,14 @@ config SERIAL_NETX_CONSOLE
 	  you can make it the console by answering Y to this option.
 
 config SERIAL_OF_PLATFORM
-	tristate "Serial port on Open Firmware platform bus"
-	depends on OF
+	tristate "Serial port on firmware platform bus"
+	depends on OF || ACPI
 	depends on SERIAL_8250 || SERIAL_OF_PLATFORM_NWPSERIAL
 	help
-	  If you have a PowerPC based system that has serial ports
-	  on a platform specific bus, you should enable this option.
-	  Currently, only 8250 compatible ports are supported, but
-	  others can easily be added.
+	  If you have a system which advertises its serial ports through
+	  devicetree or ACPI, you should enable this option. Currently
+	  only 8250 compatible and NWP ports and are supported, but others
+	  can easily be added.
 
 config SERIAL_OMAP
 	tristate "OMAP serial port support"
diff --git a/drivers/tty/serial/of_serial.c b/drivers/tty/serial/of_serial.c
index 64f1bab..54110e6 100644
--- a/drivers/tty/serial/of_serial.c
+++ b/drivers/tty/serial/of_serial.c
@@ -15,8 +15,7 @@
 #include <linux/delay.h>
 #include <linux/serial_core.h>
 #include <linux/serial_reg.h>
-#include <linux/of_address.h>
-#include <linux/of_irq.h>
+#include <linux/property.h>
 #include <linux/of_platform.h>
 #include <linux/nwpserial.h>
 #include <linux/clk.h>
@@ -54,22 +53,22 @@ static inline void tegra_serial_handle_break(struct uart_port *port)
 /*
  * Fill a struct uart_port for a given device node
  */
-static int of_platform_serial_setup(struct platform_device *ofdev,
+static int of_platform_serial_setup(struct platform_device *pdev,
 			int type, struct uart_port *port,
 			struct of_serial_info *info)
 {
-	struct resource resource;
-	struct device_node *np = ofdev->dev.of_node;
 	u32 clk, spd, prop;
-	int ret;
+	int iotype = -1;
+	u32 res_start;
+	int ret, i;
 
 	memset(port, 0, sizeof *port);
-	if (of_property_read_u32(np, "clock-frequency", &clk)) {
+	if (device_property_read_u32(&pdev->dev, "clock-frequency", &clk)) {
 
 		/* Get clk rate through clk driver if present */
-		info->clk = clk_get(&ofdev->dev, NULL);
+		info->clk = clk_get(&pdev->dev, NULL);
 		if (IS_ERR(info->clk)) {
-			dev_warn(&ofdev->dev,
+			dev_warn(&pdev->dev,
 				"clk or clock-frequency not defined\n");
 			return PTR_ERR(info->clk);
 		}
@@ -78,57 +77,63 @@ static int of_platform_serial_setup(struct platform_device *ofdev,
 		clk = clk_get_rate(info->clk);
 	}
 	/* If current-speed was set, then try not to change it. */
-	if (of_property_read_u32(np, "current-speed", &spd) == 0)
+	if (device_property_read_u32(&pdev->dev, "current-speed", &spd) == 0)
 		port->custom_divisor = clk / (16 * spd);
 
-	ret = of_address_to_resource(np, 0, &resource);
-	if (ret) {
-		dev_warn(&ofdev->dev, "invalid address\n");
+	/* Check for shifted address mapping */
+	if (device_property_read_u32(&pdev->dev, "reg-offset", &prop) != 0)
+		prop = 0;
+
+	for (i = 0; iotype == -1 && i < pdev->num_resources; i++) {
+		struct resource *resource = &pdev->resource[i];
+		if (resource_type(resource) == IORESOURCE_MEM) {
+			iotype = UPIO_MEM;
+			port->mapbase = res_start + prop;
+		} else if (resource_type(resource) == IORESOURCE_IO) {
+			iotype = UPIO_PORT;
+			port->iobase = res_start + prop;
+		}
+
+		res_start = resource->start;
+	}
+	if (iotype == -1) {
+		dev_warn(&pdev->dev, "invalid address\n");
 		goto out;
 	}
 
 	spin_lock_init(&port->lock);
-	port->mapbase = resource.start;
-
-	/* Check for shifted address mapping */
-	if (of_property_read_u32(np, "reg-offset", &prop) == 0)
-		port->mapbase += prop;
 
 	/* Check for registers offset within the devices address range */
-	if (of_property_read_u32(np, "reg-shift", &prop) == 0)
+	if (device_property_read_u32(&pdev->dev, "reg-shift", &prop) == 0)
 		port->regshift = prop;
 
 	/* Check for fifo size */
-	if (of_property_read_u32(np, "fifo-size", &prop) == 0)
+	if (device_property_read_u32(&pdev->dev, "fifo-size", &prop) == 0)
 		port->fifosize = prop;
 
-	port->irq = irq_of_parse_and_map(np, 0);
-	port->iotype = UPIO_MEM;
-	if (of_property_read_u32(np, "reg-io-width", &prop) == 0) {
-		switch (prop) {
-		case 1:
-			port->iotype = UPIO_MEM;
-			break;
-		case 4:
-			port->iotype = UPIO_MEM32;
-			break;
-		default:
-			dev_warn(&ofdev->dev, "unsupported reg-io-width (%d)\n",
+	port->irq = platform_get_irq(pdev, 0);
+
+	if (device_property_read_u32(&pdev->dev, "reg-io-width", &prop) == 0) {
+		if (prop == 4 && iotype == UPIO_MEM) {
+			iotype = UPIO_MEM32;
+		} else {
+			dev_warn(&pdev->dev, "unsupported reg-io-width (%d)\n",
 				 prop);
 			ret = -EINVAL;
 			goto out;
 		}
 	}
 
+	port->iotype = iotype;
 	port->type = type;
 	port->uartclk = clk;
 	port->flags = UPF_SHARE_IRQ | UPF_BOOT_AUTOCONF | UPF_IOREMAP
 		| UPF_FIXED_PORT | UPF_FIXED_TYPE;
 
-	if (of_find_property(np, "no-loopback-test", NULL))
+	if (device_property_present(&pdev->dev, "no-loopback-test"))
 		port->flags |= UPF_SKIP_TEST;
 
-	port->dev = &ofdev->dev;
+	port->dev = &pdev->dev;
 
 	switch (type) {
 	case PORT_TEGRA:
@@ -151,19 +156,19 @@ out:
  * Try to register a serial port
  */
 static struct of_device_id of_platform_serial_table[];
-static int of_platform_serial_probe(struct platform_device *ofdev)
+static int of_platform_serial_probe(struct platform_device *pdev)
 {
 	const struct of_device_id *match;
 	struct of_serial_info *info;
 	struct uart_port port;
 	int port_type;
 	int ret;
-
-	match = of_match_device(of_platform_serial_table, &ofdev->dev);
+	printk("%s\n", __func__);
+	match = of_match_device(of_platform_serial_table, &pdev->dev);
 	if (!match)
 		return -EINVAL;
 
-	if (of_find_property(ofdev->dev.of_node, "used-by-rtas", NULL))
+	if (device_property_present(&pdev->dev, "used-by-rtas"))
 		return -EBUSY;
 
 	info = kzalloc(sizeof(*info), GFP_KERNEL);
@@ -171,7 +176,7 @@ static int of_platform_serial_probe(struct platform_device *ofdev)
 		return -ENOMEM;
 
 	port_type = (unsigned long)match->data;
-	ret = of_platform_serial_setup(ofdev, port_type, &port, info);
+	ret = of_platform_serial_setup(pdev, port_type, &port, info);
 	if (ret)
 		goto out;
 
@@ -187,8 +192,7 @@ static int of_platform_serial_probe(struct platform_device *ofdev)
 		if (port.fifosize)
 			port8250.capabilities = UART_CAP_FIFO;
 
-		if (of_property_read_bool(ofdev->dev.of_node,
-					  "auto-flow-control"))
+		if (device_property_present(&pdev->dev, "auto-flow-control"))
 			port8250.capabilities |= UART_CAP_AFE;
 
 		ret = serial8250_register_8250_port(&port8250);
@@ -203,7 +207,7 @@ static int of_platform_serial_probe(struct platform_device *ofdev)
 	default:
 		/* need to add code for these */
 	case PORT_UNKNOWN:
-		dev_info(&ofdev->dev, "Unknown serial port found, ignored\n");
+		dev_info(&pdev->dev, "Unknown serial port found, ignored\n");
 		ret = -ENODEV;
 		break;
 	}
@@ -212,20 +216,19 @@ static int of_platform_serial_probe(struct platform_device *ofdev)
 
 	info->type = port_type;
 	info->line = ret;
-	platform_set_drvdata(ofdev, info);
+	platform_set_drvdata(pdev, info);
 	return 0;
 out:
 	kfree(info);
-	irq_dispose_mapping(port.irq);
 	return ret;
 }
 
 /*
  * Release a line
  */
-static int of_platform_serial_remove(struct platform_device *ofdev)
+static int of_platform_serial_remove(struct platform_device *pdev)
 {
-	struct of_serial_info *info = platform_get_drvdata(ofdev);
+	struct of_serial_info *info = platform_get_drvdata(pdev);
 	switch (info->type) {
 #ifdef CONFIG_SERIAL_8250
 	case PORT_8250 ... PORT_MAX_8250:

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