[linux] 01/04: [arm64] rtc: tegra: Implement clock handling (Closes: #858514)
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Thu Mar 30 00:17:38 UTC 2017
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commit 42ea80c71ca30401d0d2bbd3946ae7a0e4b60e25
Author: Ben Hutchings <ben at decadent.org.uk>
Date: Wed Mar 29 23:42:54 2017 +0100
[arm64] rtc: tegra: Implement clock handling (Closes: #858514)
---
debian/changelog | 1 +
.../arm64/rtc-tegra-implement-clock-handling.patch | 120 +++++++++++++++++++++
debian/patches/series | 1 +
3 files changed, 122 insertions(+)
diff --git a/debian/changelog b/debian/changelog
index 0458121..f22cc8b 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -144,6 +144,7 @@ linux (4.9.18-1) UNRELEASED; urgency=medium
* [x86] drm/vmwgfx: fix integer overflow in vmw_surface_define_ioctl()
(CVE-2017-7294)
* net/packet: Fix integer overflow in various range checks (CVE-2017-7308)
+ * [arm64] rtc: tegra: Implement clock handling (Closes: #858514)
-- Ben Hutchings <ben at decadent.org.uk> Mon, 27 Mar 2017 21:54:36 +0100
diff --git a/debian/patches/bugfix/arm64/rtc-tegra-implement-clock-handling.patch b/debian/patches/bugfix/arm64/rtc-tegra-implement-clock-handling.patch
new file mode 100644
index 0000000..178573f
--- /dev/null
+++ b/debian/patches/bugfix/arm64/rtc-tegra-implement-clock-handling.patch
@@ -0,0 +1,120 @@
+From: Thierry Reding <treding at nvidia.com>
+Date: Thu, 12 Jan 2017 17:07:43 +0100
+Subject: rtc: tegra: Implement clock handling
+Origin: https://git.kernel.org/linus/5fa4086987506b2ab8c92f8f99f2295db9918856
+Bug-Debian: https://bugs.debian.org/858514
+
+Accessing the registers of the RTC block on Tegra requires the module
+clock to be enabled. This only works because the RTC module clock will
+be enabled by default during early boot. However, because the clock is
+unused, the CCF will disable it at late_init time. This causes the RTC
+to become unusable afterwards. This can easily be reproduced by trying
+to use the RTC:
+
+ $ hwclock --rtc /dev/rtc1
+
+This will hang the system. I ran into this by following up on a report
+by Martin Michlmayr that reboot wasn't working on Tegra210 systems. It
+turns out that the rtc-tegra driver's ->shutdown() implementation will
+hang the CPU, because of the disabled clock, before the system can be
+rebooted.
+
+What confused me for a while is that the same driver is used on prior
+Tegra generations where the hang can not be observed. However, as Peter
+De Schrijver pointed out, this is because on 32-bit Tegra chips the RTC
+clock is enabled by the tegra20_timer.c clocksource driver, which uses
+the RTC to provide a persistent clock. This code is never enabled on
+64-bit Tegra because the persistent clock infrastructure does not exist
+on 64-bit ARM.
+
+The proper fix for this is to add proper clock handling to the RTC
+driver in order to ensure that the clock is enabled when the driver
+requires it. All device trees contain the clock already, therefore
+no additional changes are required.
+
+Reported-by: Martin Michlmayr <tbm at cyrius.com>
+Acked-By Peter De Schrijver <pdeschrijver at nvidia.com>
+Signed-off-by: Thierry Reding <treding at nvidia.com>
+Signed-off-by: Alexandre Belloni <alexandre.belloni at free-electrons.com>
+[bwh: Backported to 4.9: adjust context]
+---
+ drivers/rtc/rtc-tegra.c | 28 ++++++++++++++++++++++++++--
+ 1 file changed, 26 insertions(+), 2 deletions(-)
+
+--- a/drivers/rtc/rtc-tegra.c
++++ b/drivers/rtc/rtc-tegra.c
+@@ -18,6 +18,7 @@
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+ #include <linux/kernel.h>
++#include <linux/clk.h>
+ #include <linux/init.h>
+ #include <linux/module.h>
+ #include <linux/slab.h>
+@@ -59,6 +60,7 @@ struct tegra_rtc_info {
+ struct platform_device *pdev;
+ struct rtc_device *rtc_dev;
+ void __iomem *rtc_base; /* NULL if not initialized. */
++ struct clk *clk;
+ int tegra_rtc_irq; /* alarm and periodic irq */
+ spinlock_t tegra_rtc_lock;
+ };
+@@ -326,6 +328,14 @@ static int __init tegra_rtc_probe(struct
+ if (info->tegra_rtc_irq <= 0)
+ return -EBUSY;
+
++ info->clk = devm_clk_get(&pdev->dev, NULL);
++ if (IS_ERR(info->clk))
++ return PTR_ERR(info->clk);
++
++ ret = clk_prepare_enable(info->clk);
++ if (ret < 0)
++ return ret;
++
+ /* set context info. */
+ info->pdev = pdev;
+ spin_lock_init(&info->tegra_rtc_lock);
+@@ -346,7 +356,7 @@ static int __init tegra_rtc_probe(struct
+ ret = PTR_ERR(info->rtc_dev);
+ dev_err(&pdev->dev, "Unable to register device (err=%d).\n",
+ ret);
+- return ret;
++ goto disable_clk;
+ }
+
+ ret = devm_request_irq(&pdev->dev, info->tegra_rtc_irq,
+@@ -356,12 +366,25 @@ static int __init tegra_rtc_probe(struct
+ dev_err(&pdev->dev,
+ "Unable to request interrupt for device (err=%d).\n",
+ ret);
+- return ret;
++ goto disable_clk;
+ }
+
+ dev_notice(&pdev->dev, "Tegra internal Real Time Clock\n");
+
+ return 0;
++
++disable_clk:
++ clk_disable_unprepare(info->clk);
++ return ret;
++}
++
++static int tegra_rtc_remove(struct platform_device *pdev)
++{
++ struct tegra_rtc_info *info = platform_get_drvdata(pdev);
++
++ clk_disable_unprepare(info->clk);
++
++ return 0;
+ }
+
+ #ifdef CONFIG_PM_SLEEP
+@@ -413,6 +436,7 @@ static void tegra_rtc_shutdown(struct pl
+
+ MODULE_ALIAS("platform:tegra_rtc");
+ static struct platform_driver tegra_rtc_driver = {
++ .remove = tegra_rtc_remove,
+ .shutdown = tegra_rtc_shutdown,
+ .driver = {
+ .name = "tegra_rtc",
diff --git a/debian/patches/series b/debian/patches/series
index a6f7688..be4c517 100644
--- a/debian/patches/series
+++ b/debian/patches/series
@@ -55,6 +55,7 @@ bugfix/x86/asoc-intel-select-dw_dmac_core-since-it-s-mandatory.patch
bugfix/x86/platform-x86-acer-wmi-setup-accelerometer-when-machi.patch
bugfix/x86/x86-xen-fix-apic-id-mismatch-warning-on-intel.patch
bugfix/arm/arm-dts-kirkwood-fix-sata-pinmux-ing-for-ts419.patch
+bugfix/arm64/rtc-tegra-implement-clock-handling.patch
# Arch features
features/mips/MIPS-increase-MAX-PHYSMEM-BITS-on-Loongson-3-only.patch
--
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