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The controller used by a flexcom module is configured at boot, and left alone after this. In the suspend mode called "backup with self-refresh" available on SAMA5D2, the chip will resume with most of its registers reset. In this case, we need to restore the state of the flexcom driver on resume. Signed-off-by: Romain Izard <romain.izard.pro@gmail.com> Acked-by: Alexandre Belloni <alexandre.belloni@free-electrons.com> Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com> Tested-by: Nicolas Ferre <nicolas.ferre@microchip.com> Signed-off-by: Lee Jones <lee.jones@linaro.org>
137 lines
3.6 KiB
C
137 lines
3.6 KiB
C
/*
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* Driver for Atmel Flexcom
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*
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* Copyright (C) 2015 Atmel Corporation
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*
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* Author: Cyrille Pitchen <cyrille.pitchen@atmel.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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* This program is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*
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* You should have received a copy of the GNU General Public License along with
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* this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <linux/module.h>
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#include <linux/types.h>
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#include <linux/kernel.h>
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#include <linux/platform_device.h>
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#include <linux/of.h>
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#include <linux/of_platform.h>
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#include <linux/err.h>
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#include <linux/io.h>
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#include <linux/clk.h>
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#include <dt-bindings/mfd/atmel-flexcom.h>
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/* I/O register offsets */
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#define FLEX_MR 0x0 /* Mode Register */
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#define FLEX_VERSION 0xfc /* Version Register */
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/* Mode Register bit fields */
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#define FLEX_MR_OPMODE_OFFSET (0) /* Operating Mode */
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#define FLEX_MR_OPMODE_MASK (0x3 << FLEX_MR_OPMODE_OFFSET)
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#define FLEX_MR_OPMODE(opmode) (((opmode) << FLEX_MR_OPMODE_OFFSET) & \
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FLEX_MR_OPMODE_MASK)
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struct atmel_flexcom {
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void __iomem *base;
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u32 opmode;
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struct clk *clk;
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};
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static int atmel_flexcom_probe(struct platform_device *pdev)
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{
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struct device_node *np = pdev->dev.of_node;
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struct resource *res;
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struct atmel_flexcom *ddata;
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int err;
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ddata = devm_kzalloc(&pdev->dev, sizeof(*ddata), GFP_KERNEL);
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if (!ddata)
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return -ENOMEM;
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platform_set_drvdata(pdev, ddata);
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err = of_property_read_u32(np, "atmel,flexcom-mode", &ddata->opmode);
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if (err)
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return err;
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if (ddata->opmode < ATMEL_FLEXCOM_MODE_USART ||
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ddata->opmode > ATMEL_FLEXCOM_MODE_TWI)
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return -EINVAL;
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res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
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ddata->base = devm_ioremap_resource(&pdev->dev, res);
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if (IS_ERR(ddata->base))
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return PTR_ERR(ddata->base);
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ddata->clk = devm_clk_get(&pdev->dev, NULL);
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if (IS_ERR(ddata->clk))
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return PTR_ERR(ddata->clk);
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err = clk_prepare_enable(ddata->clk);
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if (err)
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return err;
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/*
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* Set the Operating Mode in the Mode Register: only the selected device
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* is clocked. Hence, registers of the other serial devices remain
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* inaccessible and are read as zero. Also the external I/O lines of the
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* Flexcom are muxed to reach the selected device.
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*/
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writel(FLEX_MR_OPMODE(ddata->opmode), ddata->base + FLEX_MR);
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clk_disable_unprepare(ddata->clk);
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return devm_of_platform_populate(&pdev->dev);
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}
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static const struct of_device_id atmel_flexcom_of_match[] = {
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{ .compatible = "atmel,sama5d2-flexcom" },
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{ /* sentinel */ }
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};
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MODULE_DEVICE_TABLE(of, atmel_flexcom_of_match);
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#ifdef CONFIG_PM_SLEEP
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static int atmel_flexcom_resume(struct device *dev)
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{
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struct atmel_flexcom *ddata = dev_get_drvdata(dev);
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int err;
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u32 val;
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err = clk_prepare_enable(ddata->clk);
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if (err)
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return err;
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val = FLEX_MR_OPMODE(ddata->opmode),
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writel(val, ddata->base + FLEX_MR);
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clk_disable_unprepare(ddata->clk);
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return 0;
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}
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#endif
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static SIMPLE_DEV_PM_OPS(atmel_flexcom_pm_ops, NULL,
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atmel_flexcom_resume);
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static struct platform_driver atmel_flexcom_driver = {
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.probe = atmel_flexcom_probe,
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.driver = {
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.name = "atmel_flexcom",
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.pm = &atmel_flexcom_pm_ops,
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.of_match_table = atmel_flexcom_of_match,
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},
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};
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module_platform_driver(atmel_flexcom_driver);
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MODULE_AUTHOR("Cyrille Pitchen <cyrille.pitchen@atmel.com>");
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MODULE_DESCRIPTION("Atmel Flexcom MFD driver");
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MODULE_LICENSE("GPL v2");
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