rtc: ac100: remove misuses of kernel-doc

Prevent kernel-doc warnings by changing "/**" to common comment
format "/*" in non-kernel-doc comments:

drivers/rtc/rtc-ac100.c:103: warning: This comment starts with '/**', but isn't a kernel-doc comment. Refer Documentation/doc-guide/kernel-doc.rst
* Clock controls for 3 clock output pins
drivers/rtc/rtc-ac100.c:382: warning: This comment starts with '/**', but isn't a kernel-doc comment. Refer Documentation/doc-guide/kernel-doc.rst
* RTC related bits

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Chen-Yu Tsai <wens@csie.org>
Cc: Alexandre Belloni <alexandre.belloni@bootlin.com>
Cc: <linux-rtc@vger.kernel.org>
Link: https://lore.kernel.org/r/20240114231320.31437-1-rdunlap@infradead.org
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

rtc: ac100: Convert to platform remove callback returning void

The .remove() callback for a platform driver returns an int which makes
many driver authors wrongly assume it's possible to do error handling by
returning an error code. However the value returned is (mostly) ignored
and this typically results in resource leaks. To improve here there is a
quest to make the remove callback return void. In the first step of this
quest all drivers are converted to .remove_new() which already returns
void.

Trivially convert this driver from always returning zero in the remove
callback to the void returning variant.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20230304133028.2135435-5-u.kleine-koenig@pengutronix.de
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

rtc: ac100: use rtc_lock/rtc_unlock

Avoid accessing directly rtc->ops_lock and use the RTC core helpers.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20210125221402.1958484-1-alexandre.belloni@bootlin.com

rtc: rework rtc_register_device() resource management

rtc_register_device() is a managed interface but it doesn't use devres
by itself - instead it marks an rtc_device as "registered" and the devres
callback for devm_rtc_allocate_device() takes care of resource release.

This doesn't correspond with the design behind devres where managed
structures should not be aware of being managed. The correct solution
here is to register a separate devres callback for unregistering the
device.

While at it: rename rtc_register_device() to devm_rtc_register_device()
and add it to the list of managed interfaces in devres.rst. This way we
can avoid any potential confusion of driver developers who may expect
there to exist a corresponding unregister function.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20201109163409.24301-8-brgl@bgdev.pl

rtc: remove superfluous error message

The RTC core now has error messages in case of registration failure, there
is no need to have other messages in the drivers.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20190818220041.17833-2-alexandre.belloni@bootlin.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

rtc: Remove dev_err() usage after platform_get_irq()

We don't need dev_err() messages when platform_get_irq() fails now that
platform_get_irq() prints an error message itself when something goes
wrong. Let's remove these prints with a simple semantic patch.

// <smpl>
@@
expression ret;
struct platform_device *E;
@@

ret =
(
platform_get_irq(E, ...)
|
platform_get_irq_byname(E, ...)
);

if ( \( ret < 0 \| ret <= 0 \) )
{
(
-if (ret != -EPROBE_DEFER)
-{ ...
-dev_err(...);
-... }
|
...
-dev_err(...);
)
...
}
// </smpl>

While we're here, remove braces on if statements that only have one
statement (manually).

Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: Alexandre Belloni <alexandre.belloni@bootlin.com>
Cc: linux-rtc@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Link: https://lore.kernel.org/r/20190730181557.90391-40-swboyd@chromium.org
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 174

Based on 1 normalized pattern(s):

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 as
published by the free software foundation this program is
distributed in the hope that it will be useful but without any
warranty without even the implied warranty of merchantability or
fitness for a particular purpose see the gnu general public license
for more details

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-only

has been chosen to replace the boilerplate/reference in 655 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Richard Fontana <rfontana@redhat.com>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070034.575739538@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

treewide: Use struct_size() for devm_kmalloc() and friends

Replaces open-coded struct size calculations with struct_size() for
devm_*, f2fs_*, and sock_* allocations. Automatically generated (and
manually adjusted) from the following Coccinelle script:

// Direct reference to struct field.
@@
identifier alloc =~ "devm_kmalloc|devm_kzalloc|sock_kmalloc|f2fs_kmalloc|f2fs_kzalloc";
expression HANDLE;
expression GFP;
identifier VAR, ELEMENT;
expression COUNT;
@@

- alloc(HANDLE, sizeof(*VAR) + COUNT * sizeof(*VAR->ELEMENT), GFP)
+ alloc(HANDLE, struct_size(VAR, ELEMENT, COUNT), GFP)

// mr = kzalloc(sizeof(*mr) + m * sizeof(mr->map[0]), GFP_KERNEL);
@@
identifier alloc =~ "devm_kmalloc|devm_kzalloc|sock_kmalloc|f2fs_kmalloc|f2fs_kzalloc";
expression HANDLE;
expression GFP;
identifier VAR, ELEMENT;
expression COUNT;
@@

- alloc(HANDLE, sizeof(*VAR) + COUNT * sizeof(VAR->ELEMENT[0]), GFP)
+ alloc(HANDLE, struct_size(VAR, ELEMENT, COUNT), GFP)

// Same pattern, but can't trivially locate the trailing element name,
// or variable name.
@@
identifier alloc =~ "devm_kmalloc|devm_kzalloc|sock_kmalloc|f2fs_kmalloc|f2fs_kzalloc";
expression HANDLE;
expression GFP;
expression SOMETHING, COUNT, ELEMENT;
@@

- alloc(HANDLE, sizeof(SOMETHING) + COUNT * sizeof(ELEMENT), GFP)
+ alloc(HANDLE, CHECKME_struct_size(&SOMETHING, ELEMENT, COUNT), GFP)

Signed-off-by: Kees Cook <keescook@chromium.org>

rtc: ac100: Fix ac100 determine rate bug

This patch fixes a bug, that prevents the Allwinner A83T and the A80
from a successful boot.

The bug is there since v4.16-rc1 and appeared after the clk branch was
merged.

You can find the shortend trace below:

Unable to handle kernel NULL pointer dereference at virtual address
00000000
pgd = (ptrval)
[00000000] *pgd=00000000
Internal error: Oops: 5 [#1] SMP ARM
Modules linked in:
CPU: 0 PID: 49 Comm: kworker/0:1 Not tainted 4.15.0-10190-gb89e32ccd1be #2
Hardware name: Allwinner sun8i Family
Workqueue: events deferred_probe_work_func
PC is at clk_hw_get_rate+0x0/0x34
LR is at ac100_clkout_determine_rate+0x48/0x19c

[ ... ]

(clk_hw_get_rate) from (ac100_clkout_determine_rate+0x48/0x19c)
(ac100_clkout_determine_rate) from (clk_core_set_rate_nolock+0x3c/0x1a0)
(clk_core_set_rate_nolock) from (clk_set_rate+0x30/0x88)
(clk_set_rate) from (of_clk_set_defaults+0x200/0x364)
(of_clk_set_defaults) from (platform_drv_probe+0x18/0xb0)

To fix that bug, we first check if the return of the
clk_hw_get_parent_by_index is non zero. If it is zero we skip that
clock parent.

The BUG report could be found here: https://lkml.org/lkml/2018/2/10/198

Fixes: 04940631b8d2 ("rtc: ac100: Add clk output support")

Signed-off-by: Philipp Rossak <embed3d@gmail.com>
Acked-by: Maxime Ripard <maxime.ripard@bootlin.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

rtc: stop validating rtc_time in .read_time

The RTC core is always calling rtc_valid_tm after the read_time callback.
It is not necessary to call it just before returning from the callback.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

clk: divider: fix incorrect usage of container_of

divider_recalc_rate() is an helper function used by clock divider of
different types, so the structure containing the 'hw' pointer is not
always a 'struct clk_divider'

At the following line:
> div = _get_div(table, val, flags, divider->width);

in several cases, the value of 'divider->width' is garbage as the actual
structure behind this memory is not a 'struct clk_divider'

Fortunately, this width value is used by _get_val() only when
CLK_DIVIDER_MAX_AT_ZERO flag is set. This has never been the case so
far when the structure is not a 'struct clk_divider'. This is probably
why we did not notice this bug before

Fixes: afe76c8fd030 ("clk: allow a clk divider with max divisor when zero")
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Acked-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Acked-by: Sylvain Lemieux <slemieux.tyco@gmail.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>

rtc: ac100: Fix multiple race conditions

The probe function is not allowed to fail after registering the RTC because
the following may happen:

CPU0: CPU1:
sys_load_module()
do_init_module()
do_one_initcall()
cmos_do_probe()
rtc_device_register()
__register_chrdev()
cdev->owner = struct module*
open("/dev/rtc0")
rtc_device_unregister()
module_put()
free_module()
module_free(mod->module_core)
/* struct module *module is now
freed */
chrdev_open()
spin_lock(cdev_lock)
cdev_get()
try_module_get()
module_is_live()
/* dereferences already
freed struct module* */

Also, the interrupt handler: ac100_rtc_irq() is dereferencing chip->rtc but
this may still be NULL when it is called, resulting in:
Unable to handle kernel NULL pointer dereference at virtual address 00000194
pgd = (ptrval)
[00000194] *pgd=00000000
Internal error: Oops: 5 [#1] SMP ARM
Modules linked in:
CPU: 0 PID: 72 Comm: irq/71-ac100-rt Not tainted 4.15.0-rc1-next-20171201-dirty #120
Hardware name: Allwinner sun8i Family
task: (ptrval) task.stack: (ptrval)
PC is at mutex_lock+0x14/0x3c
LR is at ac100_rtc_irq+0x38/0xc8
pc : [<c06543a4>] lr : [<c04d9a2c>] psr: 60000053
sp : ee9c9f28 ip : 00000000 fp : ee9adfdc
r10: 00000000 r9 : c0a04c48 r8 : c015ed18
r7 : ee9bd600 r6 : ee9c9f28 r5 : ee9af590 r4 : c0a04c48
r3 : ef3cb3c0 r2 : 00000000 r1 : ee9af590 r0 : 00000194
Flags: nZCv IRQs on FIQs off Mode SVC_32 ISA ARM Segment none
Control: 10c5387d Table: 4000406a DAC: 00000051
Process irq/71-ac100-rt (pid: 72, stack limit = 0x(ptrval))
Stack: (0xee9c9f28 to 0xee9ca000)
9f20: 00000000 7c2fd1be c015ed18 ee9adf40 ee9c0400 ee9c0400
9f40: ee9adf40 c015ed34 ee9c8000 ee9adf64 ee9c0400 c015f040 ee9adf80 00000000
9f60: c015ee24 7c2fd1be ee9adfc0 ee9adf80 00000000 ee9c8000 ee9adf40 c015eef4
9f80: ef1eba34 c0138f14 ee9c8000 ee9adf80 c0138df4 00000000 00000000 00000000
9fa0: 00000000 00000000 00000000 c01010e8 00000000 00000000 00000000 00000000
9fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
9fe0: 00000000 00000000 00000000 00000000 00000013 00000000 ffffffff ffffffff
[<c06543a4>] (mutex_lock) from [<c04d9a2c>] (ac100_rtc_irq+0x38/0xc8)
[<c04d9a2c>] (ac100_rtc_irq) from [<c015ed34>] (irq_thread_fn+0x1c/0x54)
[<c015ed34>] (irq_thread_fn) from [<c015f040>] (irq_thread+0x14c/0x214)
[<c015f040>] (irq_thread) from [<c0138f14>] (kthread+0x120/0x150)
[<c0138f14>] (kthread) from [<c01010e8>] (ret_from_fork+0x14/0x2c)

Solve both issues by moving to
devm_rtc_allocate_device()/rtc_register_device()

Reported-by: Quentin Schulz <quentin.schulz@free-electrons.com>
Tested-by: Quentin Schulz <quentin.schulz@free-electrons.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>

rtc: ac100: Add NULL checking for devm_kzalloc call

devm_kzalloc can return NULL, add NULL checking to prevent NULL pointer
dereference.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>

rtc: ac100: support clock-output-names in device tree binding

The ac100 device tree binding specifies the usage of clock-output-names
to specify the names of its 3 clock outputs. This is needed for orphan
clock resolution, when the ac100 is probed much later than any clocks
that consume any of its outputs. This wasn't supported by the driver.

Add support for this.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>

rtc: ac100: Add clk output support

The AC100's RTC side has 3 clock outputs on external pins, which can
provide a clock signal to the SoC or other modules, such as WiFi or
GSM modules.

Support this with a custom clk driver integrated with the rtc driver.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Acked-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

rtc: ac100: Add RTC driver for X-Powers AC100

X-Powers AC100 is a codec / RTC combo chip. This driver supports
the RTC sub-device.

The RTC block also has clock outputs and non-volatile storage.
Non-volatile storage wthin the RTC hardware is not supported.
Clock output support is added in the next patch.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Acked-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>