linux/drivers/mmc/host/sdhci-sirf.c
Stephen Warren d4d1144908 mmc: don't request CD IRQ until mmc_start_host()
As soon as the CD IRQ is requested, it can trigger, since it's an
externally controlled event. If it does, delayed_work host->detect will
be scheduled.

Many host controller probe()s are roughly structured as:

*_probe() {
    host = sdhci_pltfm_init();
    mmc_of_parse(host->mmc);
    rc = sdhci_add_host(host);
    if (rc) {
        sdhci_pltfm_free();
        return rc;
    }

In 3.17, CD IRQs can are enabled quite early via *_probe() ->
mmc_of_parse() -> mmc_gpio_request_cd() -> mmc_gpiod_request_cd_irq().

Note that in linux-next, mmc_of_parse() calls mmc_gpio*d*_request_cd()
rather than mmc_gpio_request_cd(), and mmc_gpio*d*_request_cd() doesn't
call mmc_gpiod_request_cd_irq(). However, this issue still exists if
mmc_gpio_request_cd() is called directly before mmc_start_host().

sdhci_add_host() may fail part way through (e.g. due to deferred
probe for a vmmc regulator), and sdhci_pltfm_free() does nothing to
unrequest the CD IRQ nor cancel the delayed_work. sdhci_pltfm_free() is
coded to assume that if sdhci_add_host() failed, then the delayed_work
cannot (or should not) have been triggered.

This can lead to the following with CONFIG_DEBUG_OBJECTS_* enabled, when
kfree(host) is eventually called inside sdhci_pltfm_free():

WARNING: CPU: 2 PID: 6 at lib/debugobjects.c:263 debug_print_object+0x8c/0xb4()
ODEBUG: free active (active state 0) object type: timer_list hint: delayed_work_timer_fn+0x0/0x18

The object being complained about is host->detect.

There's no need to request the CD IRQ so early; mmc_start_host() already
requests it. For most SDHCI hosts at least, the typical call path that
does this is: *_probe() -> sdhci_add_host() -> mmc_add_host() ->
mmc_start_host(). Therefore, remove the call to mmc_gpiod_request_cd_irq()
from mmc_gpio_request_cd(). This also matches mmc_gpio*d*_request_cd(),
which already doesn't call mmc_gpiod_request_cd_irq().

However, some host controller drivers call mmc_gpio_request_cd() after
mmc_start_host() has already been called, and assume that this will also
call mmc_gpiod_request_cd_irq(). Update those drivers to explicitly call
mmc_gpiod_request_cd_irq() themselves. Ideally, these drivers should be
modified to move their call to mmc_gpio_request_cd() before their call
to mmc_add_host(). However that's too large a change for stable.

This solves the problem (eliminates the kernel error message above),
since it guarantees that the IRQ can't trigger before mmc_start_host()
is called.

The critical point here is that once sdhci_add_host() calls
mmc_add_host() -> mmc_start_host(), sdhci_add_host() is coded not to
fail. In other words, if there's a chance that mmc_start_host() may have
been called, and CD IRQs triggered, and the delayed_work scheduled,
sdhci_add_host() won't fail, and so cleanup is no longer via
sdhci_pltfm_free() (which doesn't free the IRQ or cancel the work queue)
but instead must be via sdhci_remove_host(), which calls mmc_remove_host()
-> mmc_stop_host(), which does free the IRQ and cancel the work queue.

CC: Russell King <linux@arm.linux.org.uk>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexandre Courbot <acourbot@nvidia.com>
Cc: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: <stable@vger.kernel.org> # v3.15+
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
2014-09-23 09:01:36 +02:00

207 lines
4.8 KiB
C

/*
* SDHCI support for SiRF primaII and marco SoCs
*
* Copyright (c) 2011 Cambridge Silicon Radio Limited, a CSR plc group company.
*
* Licensed under GPLv2 or later.
*/
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/mmc/host.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_gpio.h>
#include <linux/mmc/slot-gpio.h>
#include "sdhci-pltfm.h"
#define SDHCI_SIRF_8BITBUS BIT(3)
struct sdhci_sirf_priv {
struct clk *clk;
int gpio_cd;
};
static unsigned int sdhci_sirf_get_max_clk(struct sdhci_host *host)
{
struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
struct sdhci_sirf_priv *priv = sdhci_pltfm_priv(pltfm_host);
return clk_get_rate(priv->clk);
}
static void sdhci_sirf_set_bus_width(struct sdhci_host *host, int width)
{
u8 ctrl;
ctrl = sdhci_readb(host, SDHCI_HOST_CONTROL);
ctrl &= ~(SDHCI_CTRL_4BITBUS | SDHCI_SIRF_8BITBUS);
/*
* CSR atlas7 and prima2 SD host version is not 3.0
* 8bit-width enable bit of CSR SD hosts is 3,
* while stardard hosts use bit 5
*/
if (width == MMC_BUS_WIDTH_8)
ctrl |= SDHCI_SIRF_8BITBUS;
else if (width == MMC_BUS_WIDTH_4)
ctrl |= SDHCI_CTRL_4BITBUS;
sdhci_writeb(host, ctrl, SDHCI_HOST_CONTROL);
}
static struct sdhci_ops sdhci_sirf_ops = {
.set_clock = sdhci_set_clock,
.get_max_clock = sdhci_sirf_get_max_clk,
.set_bus_width = sdhci_sirf_set_bus_width,
.reset = sdhci_reset,
.set_uhs_signaling = sdhci_set_uhs_signaling,
};
static struct sdhci_pltfm_data sdhci_sirf_pdata = {
.ops = &sdhci_sirf_ops,
.quirks = SDHCI_QUIRK_BROKEN_TIMEOUT_VAL |
SDHCI_QUIRK_DATA_TIMEOUT_USES_SDCLK |
SDHCI_QUIRK_CAP_CLOCK_BASE_BROKEN |
SDHCI_QUIRK_INVERTED_WRITE_PROTECT |
SDHCI_QUIRK_DELAY_AFTER_POWER,
};
static int sdhci_sirf_probe(struct platform_device *pdev)
{
struct sdhci_host *host;
struct sdhci_pltfm_host *pltfm_host;
struct sdhci_sirf_priv *priv;
struct clk *clk;
int gpio_cd;
int ret;
clk = devm_clk_get(&pdev->dev, NULL);
if (IS_ERR(clk)) {
dev_err(&pdev->dev, "unable to get clock");
return PTR_ERR(clk);
}
if (pdev->dev.of_node)
gpio_cd = of_get_named_gpio(pdev->dev.of_node, "cd-gpios", 0);
else
gpio_cd = -EINVAL;
host = sdhci_pltfm_init(pdev, &sdhci_sirf_pdata, sizeof(struct sdhci_sirf_priv));
if (IS_ERR(host))
return PTR_ERR(host);
pltfm_host = sdhci_priv(host);
priv = sdhci_pltfm_priv(pltfm_host);
priv->clk = clk;
priv->gpio_cd = gpio_cd;
sdhci_get_of_property(pdev);
ret = clk_prepare_enable(priv->clk);
if (ret)
goto err_clk_prepare;
ret = sdhci_add_host(host);
if (ret)
goto err_sdhci_add;
/*
* We must request the IRQ after sdhci_add_host(), as the tasklet only
* gets setup in sdhci_add_host() and we oops.
*/
if (gpio_is_valid(priv->gpio_cd)) {
ret = mmc_gpio_request_cd(host->mmc, priv->gpio_cd, 0);
if (ret) {
dev_err(&pdev->dev, "card detect irq request failed: %d\n",
ret);
goto err_request_cd;
}
mmc_gpiod_request_cd_irq(host->mmc);
}
return 0;
err_request_cd:
sdhci_remove_host(host, 0);
err_sdhci_add:
clk_disable_unprepare(priv->clk);
err_clk_prepare:
sdhci_pltfm_free(pdev);
return ret;
}
static int sdhci_sirf_remove(struct platform_device *pdev)
{
struct sdhci_host *host = platform_get_drvdata(pdev);
struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
struct sdhci_sirf_priv *priv = sdhci_pltfm_priv(pltfm_host);
sdhci_pltfm_unregister(pdev);
if (gpio_is_valid(priv->gpio_cd))
mmc_gpio_free_cd(host->mmc);
clk_disable_unprepare(priv->clk);
return 0;
}
#ifdef CONFIG_PM_SLEEP
static int sdhci_sirf_suspend(struct device *dev)
{
struct sdhci_host *host = dev_get_drvdata(dev);
struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
struct sdhci_sirf_priv *priv = sdhci_pltfm_priv(pltfm_host);
int ret;
ret = sdhci_suspend_host(host);
if (ret)
return ret;
clk_disable(priv->clk);
return 0;
}
static int sdhci_sirf_resume(struct device *dev)
{
struct sdhci_host *host = dev_get_drvdata(dev);
struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
struct sdhci_sirf_priv *priv = sdhci_pltfm_priv(pltfm_host);
int ret;
ret = clk_enable(priv->clk);
if (ret) {
dev_dbg(dev, "Resume: Error enabling clock\n");
return ret;
}
return sdhci_resume_host(host);
}
static SIMPLE_DEV_PM_OPS(sdhci_sirf_pm_ops, sdhci_sirf_suspend, sdhci_sirf_resume);
#endif
static const struct of_device_id sdhci_sirf_of_match[] = {
{ .compatible = "sirf,prima2-sdhc" },
{ }
};
MODULE_DEVICE_TABLE(of, sdhci_sirf_of_match);
static struct platform_driver sdhci_sirf_driver = {
.driver = {
.name = "sdhci-sirf",
.of_match_table = sdhci_sirf_of_match,
#ifdef CONFIG_PM_SLEEP
.pm = &sdhci_sirf_pm_ops,
#endif
},
.probe = sdhci_sirf_probe,
.remove = sdhci_sirf_remove,
};
module_platform_driver(sdhci_sirf_driver);
MODULE_DESCRIPTION("SDHCI driver for SiRFprimaII/SiRFmarco");
MODULE_AUTHOR("Barry Song <21cnbao@gmail.com>");
MODULE_LICENSE("GPL v2");