arch/arm/mach-imx/low_system_bus.c

/*
 * Copyright (C) 2015 Freescale Semiconductor, Inc.
 *
 * The code contained herein is licensed under the GNU General Public
 * License. You may obtain a copy of the GNU General Public License
 * Version 2 or later at the following locations:
 *
 * http://www.opensource.org/licenses/gpl-license.html
 * http://www.gnu.org/copyleft/gpl.html
 */

#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/io.h>
#include <linux/irq.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/platform_device.h>

#include "clk.h"
#include "common.h"
#include "hardware.h"

#define NORMAL_AHB_FREQ		132000000
#define LOW_AHB_FREQ		24000000
#define LOW_OCRAM_FREQ		24000000
#define LOW_DISPLAY_AXI_FREQ	66000000

static struct device *low_system_bus_dev;
static struct clk *ahb, *ipg, *periph, *periph_pre,
	*periph_clk2, *periph_clk2_sel, *osc, *ocram_sel, *ocram, *display_podf,
	*ecspi_sel, *uart_sel, *gpu_core_sel, *gpu_axi_sel, *pll2;

#ifdef CONFIG_PM_SLEEP
static int imx6sx_low_system_bus_suspend(struct device *dev)
{
	/* make sure AHB&IPG divider is correct before changing periph clk parent */
	clk_set_rate(ipg, LOW_AHB_FREQ / 2);
	clk_set_rate(ahb, LOW_AHB_FREQ / 3);
	imx_clk_set_parent(periph, periph_pre);
	clk_set_rate(ahb, NORMAL_AHB_FREQ);
	clk_set_rate(ipg, NORMAL_AHB_FREQ / 2);

	return 0;
}

static int imx6sx_low_system_bus_resume(struct device *dev)
{
	imx_clk_set_parent(periph, periph_clk2);
	clk_set_rate(ahb, LOW_AHB_FREQ);
	clk_set_rate(ipg, LOW_AHB_FREQ / 2);

	return 0;
}
#endif

static int imx_low_system_bus_probe(struct platform_device *pdev)
{
	low_system_bus_dev = &pdev->dev;

	ahb = devm_clk_get(low_system_bus_dev, "ahb");
	ipg = devm_clk_get(low_system_bus_dev, "ipg");
	periph = devm_clk_get(low_system_bus_dev, "periph");
	periph_pre = devm_clk_get(low_system_bus_dev, "periph_pre");
	periph_clk2 = devm_clk_get(low_system_bus_dev, "periph_clk2");
	periph_clk2_sel = devm_clk_get(low_system_bus_dev, "periph_clk2_sel");
	osc = devm_clk_get(low_system_bus_dev, "osc");
	ocram_sel = devm_clk_get(low_system_bus_dev, "ocram_sel");
	ocram = devm_clk_get(low_system_bus_dev, "ocram");
	display_podf = devm_clk_get(low_system_bus_dev, "display_podf");
	ecspi_sel = devm_clk_get(low_system_bus_dev, "ecspi_sel");
	uart_sel = devm_clk_get(low_system_bus_dev, "uart_sel");
	gpu_core_sel = devm_clk_get(low_system_bus_dev, "gpu_core_sel");
	gpu_axi_sel = devm_clk_get(low_system_bus_dev, "gpu_axi_sel");
	pll2 = devm_clk_get(low_system_bus_dev, "pll2");

	if (IS_ERR(ahb) || IS_ERR(ipg)
		|| IS_ERR(periph) || IS_ERR(periph_pre)
		|| IS_ERR(periph_clk2) || IS_ERR(periph_clk2_sel)
		|| IS_ERR(osc) || IS_ERR(ocram_sel) || IS_ERR(ocram)
		|| IS_ERR(display_podf) || IS_ERR(ecspi_sel) || IS_ERR(uart_sel)
		|| IS_ERR(gpu_core_sel) || IS_ERR(gpu_axi_sel) || IS_ERR(pll2)) {
		dev_err(low_system_bus_dev, "failed to get all necessary clks!\n");
		return -ENOENT;
	}

	imx_clk_set_parent(periph_clk2_sel, osc);
	imx_clk_set_parent(periph, periph_clk2);
	clk_set_rate(ahb, LOW_AHB_FREQ);
	clk_set_rate(ipg, LOW_AHB_FREQ / 2);
	imx_clk_set_parent(ocram_sel, periph);
	clk_set_rate(ocram, LOW_OCRAM_FREQ);
	clk_set_rate(display_podf, LOW_DISPLAY_AXI_FREQ);
	imx_clk_set_parent(uart_sel, osc);
	imx_clk_set_parent(ecspi_sel, osc);
    //avoid gpu clock reconfiguration for now. keeping the code.
	//imx_clk_set_parent(gpu_core_sel, pll2);
	//imx_clk_set_parent(gpu_axi_sel, pll2);
	pr_info("set AHB/IPG to 24MHz/12MHz, OCRAM to 24MHz, DISPLAY_AXI to 66MHz\n");

	pr_info("imx low system bus driver probed!\n");

	return 0;
}

#ifdef CONFIG_PM_SLEEP
static SIMPLE_DEV_PM_OPS(imx6sx_low_system_bus_pm_ops,
			 imx6sx_low_system_bus_suspend, imx6sx_low_system_bus_resume);
#endif

static const struct of_device_id imx_low_system_bus_ids[] = {
	{ .compatible = "fsl,imx6sx-low_system_bus" },
};
MODULE_DEVICE_TABLE(of, imx_low_system_bus_ids);

static struct platform_driver imx_low_system_bus_platdrv = {
	.driver = {
		.name	= "imx-low-system-bus",
		.owner	= THIS_MODULE,
#ifdef CONFIG_PM_SLEEP
		.pm	= &imx6sx_low_system_bus_pm_ops,
#endif
		.of_match_table = imx_low_system_bus_ids,
	},
	.probe		= imx_low_system_bus_probe,
};

static int __init imx6_low_system_bus_init(void)
{
	return platform_driver_probe(&imx_low_system_bus_platdrv, imx_low_system_bus_probe);
}
fs_initcall(imx6_low_system_bus_init);

MODULE_AUTHOR("Anson Huang <b20788@freescale.com>");
MODULE_DESCRIPTION("Freescale i.MX low system bus driver");
MODULE_LICENSE("GPL");