linux-kernel - [PATCH 4.2.y-ckt 210/218] clk: versatile: sp810: support reentrance

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Message-Id: <1459455431-12687-211-git-send-email-kamal@canonical.com>
Date:	Thu, 31 Mar 2016 13:17:03 -0700
From:	Kamal Mostafa <kamal@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Michael Turquette <mturquette@...libre.com>,
	Pawel Moll <pawel.moll@....com>,
	Linus Walleij <linus.walleij@...aro.org>,
	Stephen Boyd <sboyd@...eaurora.org>,
	Kamal Mostafa <kamal@...onical.com>
Subject: [PATCH 4.2.y-ckt 210/218] clk: versatile: sp810: support reentrance

4.2.8-ckt7 -stable review patch.  If anyone has any objections, please let me know.

---8<------------------------------------------------------------

From: Linus Walleij <linus.walleij@...aro.org>

commit ec7957a6aa0aaf981fb8356dc47a2cdd01cde03c upstream.

Despite care take to allocate clocks state containers the
SP810 driver actually just supports creating one instance:
all clocks registered for every instance will end up with the
exact same name and __clk_init() will fail.

Rename the timclken<0> .. timclken<n> to sp810_<instance>_<n>
so every clock on every instance gets a unique name.

This is necessary for the RealView PBA8 which has two SP810
blocks: the second block will not register its clocks unless
every clock on every instance is unique and results in boot
logs like this:

------------[ cut here ]------------
WARNING: CPU: 0 PID: 0 at ../drivers/clk/versatile/clk-sp810.c:137
  clk_sp810_of_setup+0x110/0x154()
Modules linked in:
CPU: 0 PID: 0 Comm: swapper/0 Not tainted
4.5.0-rc2-00030-g352718fc39f6-dirty #225
Hardware name: ARM RealView Machine (Device Tree Support)
[<c00167f8>] (unwind_backtrace) from [<c0013204>]
             (show_stack+0x10/0x14)
[<c0013204>] (show_stack) from [<c01a049c>]
             (dump_stack+0x84/0x9c)
[<c01a049c>] (dump_stack) from [<c0024990>]
             (warn_slowpath_common+0x74/0xb0)
[<c0024990>] (warn_slowpath_common) from [<c0024a68>]
             (warn_slowpath_null+0x1c/0x24)
[<c0024a68>] (warn_slowpath_null) from [<c051eb44>]
             (clk_sp810_of_setup+0x110/0x154)
[<c051eb44>] (clk_sp810_of_setup) from [<c051e3a4>]
             (of_clk_init+0x12c/0x1c8)
[<c051e3a4>] (of_clk_init) from [<c0504714>]
             (time_init+0x20/0x2c)
[<c0504714>] (time_init) from [<c0501b18>]
             (start_kernel+0x244/0x3c4)
[<c0501b18>] (start_kernel) from [<7000807c>] (0x7000807c)
---[ end trace cb88537fdc8fa200 ]---

Cc: Michael Turquette <mturquette@...libre.com>
Cc: Pawel Moll <pawel.moll@....com>
Fixes: 6e973d2c4385 "clk: vexpress: Add separate SP810 driver"
Signed-off-by: Linus Walleij <linus.walleij@...aro.org>
Signed-off-by: Stephen Boyd <sboyd@...eaurora.org>
Signed-off-by: Kamal Mostafa <kamal@...onical.com>
---
 drivers/clk/versatile/clk-sp810.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/clk/versatile/clk-sp810.c b/drivers/clk/versatile/clk-sp810.c
index b674ffc..72af18b 100644
--- a/drivers/clk/versatile/clk-sp810.c
+++ b/drivers/clk/versatile/clk-sp810.c
@@ -141,6 +141,7 @@ static void __init clk_sp810_of_setup(struct device_node *node)
 	const char *parent_names[2];
 	char name[12];
 	struct clk_init_data init;
+	static int instance;
 	int i;
 
 	if (!sp810) {
@@ -172,7 +173,7 @@ static void __init clk_sp810_of_setup(struct device_node *node)
 	init.num_parents = ARRAY_SIZE(parent_names);
 
 	for (i = 0; i < ARRAY_SIZE(sp810->timerclken); i++) {
-		snprintf(name, ARRAY_SIZE(name), "timerclken%d", i);
+		snprintf(name, sizeof(name), "sp810_%d_%d", instance, i);
 
 		sp810->timerclken[i].sp810 = sp810;
 		sp810->timerclken[i].channel = i;
@@ -184,5 +185,6 @@ static void __init clk_sp810_of_setup(struct device_node *node)
 	}
 
 	of_clk_add_provider(node, clk_sp810_timerclken_of_get, sp810);
+	instance++;
 }
 CLK_OF_DECLARE(sp810, "arm,sp810", clk_sp810_of_setup);
-- 
2.7.4