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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>
49 lines
1.1 KiB
C
49 lines
1.1 KiB
C
/*
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* Intel Lynxpoint LPSS clocks.
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*
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* Copyright (C) 2013, Intel Corporation
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* Authors: Mika Westerberg <mika.westerberg@linux.intel.com>
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* Heikki Krogerus <heikki.krogerus@linux.intel.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/clk.h>
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#include <linux/clkdev.h>
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#include <linux/clk-provider.h>
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#include <linux/err.h>
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#include <linux/module.h>
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#include <linux/platform_device.h>
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#define PRV_CLOCK_PARAMS 0x800
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static int lpt_clk_probe(struct platform_device *pdev)
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{
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struct clk *clk;
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/* LPSS free running clock */
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clk = clk_register_fixed_rate(&pdev->dev, "lpss_clk", NULL, CLK_IS_ROOT,
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100000000);
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if (IS_ERR(clk))
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return PTR_ERR(clk);
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/* Shared DMA clock */
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clk_register_clkdev(clk, "hclk", "INTL9C60.0.auto");
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return 0;
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}
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static struct platform_driver lpt_clk_driver = {
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.driver = {
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.name = "clk-lpt",
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.owner = THIS_MODULE,
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},
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.probe = lpt_clk_probe,
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};
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int __init lpt_clk_init(void)
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{
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return platform_driver_register(&lpt_clk_driver);
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}
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