52c8212d80
In case if a pwrseq-emmc has been bound to the host, a call to mmc_power_up() triggers an eMMC HW reset via the pwrseq_emmc's ->post_power_on() callback. This isn't really what we want, as mmc_power_up() is called each time when resuming the card. As a matter of fact, the current approach may also violate the eMMC spec, as the involved delays managed in pwrseq_emmc assumes both VCC and VCCQ has been turned on, which isn't the case for VCCQ, unless the regulator is always on. Fix this behaviour by aligning to the same procedure used when the mmc host implements the ->hw_reset() callback and has the MMC_CAP_HW_RESET flag set. In this way the eMMC HW reset is issued at card detection scan, to cope with bogus bootloaders and in the error recovery path via the mmc specific bus_ops->reset() callback. Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org> Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
120 lines
3 KiB
C
120 lines
3 KiB
C
/*
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* Copyright (C) 2015, Samsung Electronics Co., Ltd.
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*
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* Author: Marek Szyprowski <m.szyprowski@samsung.com>
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*
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* License terms: GNU General Public License (GPL) version 2
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*
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* Simple eMMC hardware reset provider
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*/
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#include <linux/delay.h>
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#include <linux/kernel.h>
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#include <linux/init.h>
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#include <linux/platform_device.h>
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/device.h>
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#include <linux/err.h>
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#include <linux/gpio/consumer.h>
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#include <linux/reboot.h>
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#include <linux/mmc/host.h>
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#include "pwrseq.h"
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struct mmc_pwrseq_emmc {
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struct mmc_pwrseq pwrseq;
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struct notifier_block reset_nb;
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struct gpio_desc *reset_gpio;
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};
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#define to_pwrseq_emmc(p) container_of(p, struct mmc_pwrseq_emmc, pwrseq)
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static void __mmc_pwrseq_emmc_reset(struct mmc_pwrseq_emmc *pwrseq)
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{
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gpiod_set_value(pwrseq->reset_gpio, 1);
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udelay(1);
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gpiod_set_value(pwrseq->reset_gpio, 0);
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udelay(200);
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}
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static void mmc_pwrseq_emmc_reset(struct mmc_host *host)
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{
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struct mmc_pwrseq_emmc *pwrseq = to_pwrseq_emmc(host->pwrseq);
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__mmc_pwrseq_emmc_reset(pwrseq);
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}
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static int mmc_pwrseq_emmc_reset_nb(struct notifier_block *this,
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unsigned long mode, void *cmd)
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{
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struct mmc_pwrseq_emmc *pwrseq = container_of(this,
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struct mmc_pwrseq_emmc, reset_nb);
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__mmc_pwrseq_emmc_reset(pwrseq);
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return NOTIFY_DONE;
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}
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static const struct mmc_pwrseq_ops mmc_pwrseq_emmc_ops = {
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.reset = mmc_pwrseq_emmc_reset,
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};
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static int mmc_pwrseq_emmc_probe(struct platform_device *pdev)
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{
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struct mmc_pwrseq_emmc *pwrseq;
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struct device *dev = &pdev->dev;
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pwrseq = devm_kzalloc(dev, sizeof(*pwrseq), GFP_KERNEL);
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if (!pwrseq)
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return -ENOMEM;
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pwrseq->reset_gpio = devm_gpiod_get(dev, "reset", GPIOD_OUT_LOW);
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if (IS_ERR(pwrseq->reset_gpio))
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return PTR_ERR(pwrseq->reset_gpio);
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/*
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* register reset handler to ensure emmc reset also from
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* emergency_reboot(), priority 255 is the highest priority
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* so it will be executed before any system reboot handler.
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*/
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pwrseq->reset_nb.notifier_call = mmc_pwrseq_emmc_reset_nb;
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pwrseq->reset_nb.priority = 255;
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register_restart_handler(&pwrseq->reset_nb);
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pwrseq->pwrseq.ops = &mmc_pwrseq_emmc_ops;
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pwrseq->pwrseq.dev = dev;
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pwrseq->pwrseq.owner = THIS_MODULE;
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platform_set_drvdata(pdev, pwrseq);
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return mmc_pwrseq_register(&pwrseq->pwrseq);
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}
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static int mmc_pwrseq_emmc_remove(struct platform_device *pdev)
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{
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struct mmc_pwrseq_emmc *pwrseq = platform_get_drvdata(pdev);
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unregister_restart_handler(&pwrseq->reset_nb);
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mmc_pwrseq_unregister(&pwrseq->pwrseq);
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return 0;
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}
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static const struct of_device_id mmc_pwrseq_emmc_of_match[] = {
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{ .compatible = "mmc-pwrseq-emmc",},
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{/* sentinel */},
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};
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MODULE_DEVICE_TABLE(of, mmc_pwrseq_emmc_of_match);
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static struct platform_driver mmc_pwrseq_emmc_driver = {
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.probe = mmc_pwrseq_emmc_probe,
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.remove = mmc_pwrseq_emmc_remove,
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.driver = {
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.name = "pwrseq_emmc",
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.of_match_table = mmc_pwrseq_emmc_of_match,
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},
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};
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module_platform_driver(mmc_pwrseq_emmc_driver);
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MODULE_LICENSE("GPL v2");
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