ACPI / scan: Add special handler for Intel Lynxpoint LPSS devices

Devices on the Intel Lynxpoint Low Power Subsystem (LPSS) have some
common features that aren't shared with any other platform devices,
including the clock and LTR (Latency Tolerance Reporting) registers.
It is better to handle those features in common code than to bother
device drivers with doing that (I/O functionality-wise the LPSS
devices are generally compatible with other devices that don't
have those special registers and may be handled by the same drivers).

The clock registers of the LPSS devices are now taken care of by
the special clk-x86-lpss driver, but the MMIO mappings used for
accessing those registers can also be used for accessing the LTR
registers on those devices (LTR support for the Lynxpoint LPSS is
going to be added by a subsequent patch).  Thus it is convenient
to add a special ACPI scan handler for the Lynxpoint LPSS devices
that will create the MMIO mappings for accessing the clock (and
LTR in the future) registers and will register the LPSS devices'
clocks, so the clk-x86-lpss driver will only need to take care of
the main Lynxpoint LPSS clock.

Introduce a special ACPI scan handler for Intel Lynxpoint LPSS
devices as described above.  This also reduces overhead related to
browsing the ACPI namespace in search of the LPSS devices before the
registration of their clocks, removes some LPSS-specific (and
somewhat ugly) code from acpi_platform.c and shrinks the overall code
size slightly.

Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Mike Turquette <mturquette@linaro.org>

1 files changed, 163 insertions, 0 deletions

diff --git a/drivers/acpi/acpi_lpss.c b/drivers/acpi/acpi_lpss.c
new file mode 100644
index 00000000000..823df46a3de
--- /dev/null
+++ b/drivers/acpi/acpi_lpss.c
@@ -0,0 +1,163 @@
+/*
+ * ACPI support for Intel Lynxpoint LPSS.
+ *
+ * Copyright (C) 2013, Intel Corporation
+ * Authors: Mika Westerberg <mika.westerberg@linux.intel.com>
+ *          Rafael J. Wysocki <rafael.j.wysocki@intel.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/acpi.h>
+#include <linux/clk.h>
+#include <linux/clkdev.h>
+#include <linux/clk-provider.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/platform_device.h>
+#include <linux/platform_data/clk-lpss.h>
+
+#include "internal.h"
+
+ACPI_MODULE_NAME("acpi_lpss");
+
+#define LPSS_CLK_OFFSET 0x800
+#define LPSS_CLK_SIZE	0x04
+
+struct lpss_device_desc {
+	bool clk_required;
+	const char *clk_parent;
+};
+
+struct lpss_private_data {
+	void __iomem *mmio_base;
+	resource_size_t mmio_size;
+	struct clk *clk;
+	const struct lpss_device_desc *dev_desc;
+};
+
+static struct lpss_device_desc lpt_dev_desc = {
+	.clk_required = true,
+	.clk_parent = "lpss_clk",
+};
+
+static const struct acpi_device_id acpi_lpss_device_ids[] = {
+	/* Lynxpoint LPSS devices */
+	{ "INT33C0", (unsigned long)&lpt_dev_desc },
+	{ "INT33C1", (unsigned long)&lpt_dev_desc },
+	{ "INT33C2", (unsigned long)&lpt_dev_desc },
+	{ "INT33C3", (unsigned long)&lpt_dev_desc },
+	{ "INT33C4", (unsigned long)&lpt_dev_desc },
+	{ "INT33C5", (unsigned long)&lpt_dev_desc },
+	{ "INT33C6", },
+	{ "INT33C7", },
+
+	{ }
+};
+
+static int is_memory(struct acpi_resource *res, void *not_used)
+{
+	struct resource r;
+	return !acpi_dev_resource_memory(res, &r);
+}
+
+/* LPSS main clock device. */
+static struct platform_device *lpss_clk_dev;
+
+static inline void lpt_register_clock_device(void)
+{
+	lpss_clk_dev = platform_device_register_simple("clk-lpt", -1, NULL, 0);
+}
+
+static int register_device_clock(struct acpi_device *adev,
+				 struct lpss_private_data *pdata)
+{
+	const struct lpss_device_desc *dev_desc = pdata->dev_desc;
+
+	if (!lpss_clk_dev)
+		lpt_register_clock_device();
+
+	if (!dev_desc->clk_parent || !pdata->mmio_base
+	    || pdata->mmio_size < LPSS_CLK_OFFSET + LPSS_CLK_SIZE)
+		return -ENODATA;
+
+	pdata->clk = clk_register_gate(NULL, dev_name(&adev->dev),
+				       dev_desc->clk_parent, 0,
+				       pdata->mmio_base + LPSS_CLK_OFFSET,
+				       0, 0, NULL);
+	if (IS_ERR(pdata->clk))
+		return PTR_ERR(pdata->clk);
+
+	clk_register_clkdev(pdata->clk, NULL, dev_name(&adev->dev));
+	return 0;
+}
+
+static int acpi_lpss_create_device(struct acpi_device *adev,
+				   const struct acpi_device_id *id)
+{
+	struct lpss_device_desc *dev_desc;
+	struct lpss_private_data *pdata;
+	struct resource_list_entry *rentry;
+	struct list_head resource_list;
+	int ret;
+
+	dev_desc = (struct lpss_device_desc *)id->driver_data;
+	if (!dev_desc)
+		return acpi_create_platform_device(adev, id);
+
+	pdata = kzalloc(sizeof(*pdata), GFP_KERNEL);
+	if (!pdata)
+		return -ENOMEM;
+
+	INIT_LIST_HEAD(&resource_list);
+	ret = acpi_dev_get_resources(adev, &resource_list, is_memory, NULL);
+	if (ret < 0)
+		goto err_out;
+
+	list_for_each_entry(rentry, &resource_list, node)
+		if (resource_type(&rentry->res) == IORESOURCE_MEM) {
+			pdata->mmio_size = resource_size(&rentry->res);
+			pdata->mmio_base = ioremap(rentry->res.start,
+						   pdata->mmio_size);
+			pdata->dev_desc = dev_desc;
+			break;
+		}
+
+	acpi_dev_free_resource_list(&resource_list);
+
+	if (dev_desc->clk_required) {
+		ret = register_device_clock(adev, pdata);
+		if (ret) {
+			/*
+			 * Skip the device, but don't terminate the namespace
+			 * scan.
+			 */
+			ret = 0;
+			goto err_out;
+		}
+	}
+
+	adev->driver_data = pdata;
+	ret = acpi_create_platform_device(adev, id);
+	if (ret > 0)
+		return ret;
+
+	adev->driver_data = NULL;
+
+ err_out:
+	kfree(pdata);
+	return ret;
+}
+
+static struct acpi_scan_handler lpss_handler = {
+	.ids = acpi_lpss_device_ids,
+	.attach = acpi_lpss_create_device,
+};
+
+void __init acpi_lpss_init(void)
+{
+	if (!lpt_clk_init())
+		acpi_scan_add_handler(&lpss_handler);
+}