oxnas: clk-oxnas: rework pllb enable function

kernel lock debugging unveiled that we should not call
of_reset_control_get inside a clock's enable operation (see below)

move of_reset_control_* previously used in pllb_clk_enable to new
pllb_clk_prepare and pllb_clk_unprepare functions.
use a container to carry runtime information.

------------[ cut here ]------------
WARNING: CPU: 0 PID: 1 at kernel/locking/lockdep.c:2742 lockdep_trace_alloc+0xb8/0xfc()
DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags))
Modules linked in:
CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.14.26 #6
[<c001a6ac>] (unwind_backtrace) from [<c0016dec>] (show_stack+0x10/0x14)
[<c0016dec>] (show_stack) from [<c0194f68>] (dump_stack+0x7c/0x94)
[<c0194f68>] (dump_stack) from [<c0021b50>] (warn_slowpath_common+0x68/0x8c)
[<c0021b50>] (warn_slowpath_common) from [<c0021ba4>] (warn_slowpath_fmt+0x30/0x40)
[<c0021ba4>] (warn_slowpath_fmt) from [<c0061b30>] (lockdep_trace_alloc+0xb8/0xfc)
[<c0061b30>] (lockdep_trace_alloc) from [<c00cb740>] (kmem_cache_alloc+0x1c/0xf8)
[<c00cb740>] (kmem_cache_alloc) from [<c01d33c8>] (of_reset_control_get+0xe8/0x12c)
[<c01d33c8>] (of_reset_control_get) from [<c0269228>] (pllb_clk_enable+0x14/0xbc)
[<c0269228>] (pllb_clk_enable) from [<c0265738>] (__clk_enable+0x54/0xa0)
[<c0265738>] (__clk_enable) from [<c0265acc>] (clk_enable+0x18/0x2c)
[<c0265acc>] (clk_enable) from [<c04325f8>] (oxnas_pcie_probe+0x3b8/0x6a0)
[<c04325f8>] (oxnas_pcie_probe) from [<c01f2510>] (platform_drv_probe+0x18/0x48)
[<c01f2510>] (platform_drv_probe) from [<c01f1070>] (driver_probe_device+0xd8/0x24c)
[<c01f1070>] (driver_probe_device) from [<c01f1298>] (__driver_attach+0x70/0x94)
[<c01f1298>] (__driver_attach) from [<c01ef728>] (bus_for_each_dev+0x4c/0x98)
[<c01ef728>] (bus_for_each_dev) from [<c01f0818>] (bus_add_driver+0xcc/0x1e8)
[<c01f0818>] (bus_add_driver) from [<c01f169c>] (driver_register+0xa0/0xe8)
[<c01f169c>] (driver_register) from [<c01f2568>] (platform_driver_probe+0x20/0xa4)
[<c01f2568>] (platform_driver_probe) from [<c0013a3c>] (do_one_initcall+0x90/0x140)
[<c0013a3c>] (do_one_initcall) from [<c0421d38>] (kernel_init_freeable+0x1e4/0x2c0)
[<c0421d38>] (kernel_init_freeable) from [<c000c214>] (kernel_init+0x8/0x104)
[<c000c214>] (kernel_init) from [<c0008768>] (ret_from_fork+0x14/0x2c)
---[ end trace 5f17ed2f61e0683f ]---

Signed-off-by: Daniel Golle <daniel@makrotopia.org>

SVN-Revision: 43787

target/linux/oxnas/files/drivers/clk/clk-oxnas.c

@@ -28,6 +28,14 @@
 
 #define MHZ (1000 * 1000)
 
+struct clk_oxnas_pllb {
+	struct clk_hw hw;
+	struct device_node *devnode;
+	struct reset_control *rstc;
+};
+
+#define to_clk_oxnas_pllb(_hw) container_of(_hw, struct clk_oxnas_pllb, hw)
+
 static unsigned long plla_clk_recalc_rate(struct clk_hw *hw,
 	unsigned long parent_rate)
 {
@@ -67,48 +75,72 @@ static struct clk_hw plla_hw = {
 	.init = &clk_plla_init,
 };
 
-static struct device_node *node_pllb;
+static int pllb_clk_is_prepared(struct clk_hw *hw)
+{
+	struct clk_oxnas_pllb *pllb = to_clk_oxnas_pllb(hw);
+
+	return !!pllb->rstc;
+}
 
-int pllb_clk_enable(struct clk_hw *hw)
+static int pllb_clk_prepare(struct clk_hw *hw)
 {
-	struct reset_control *rstc;
+	struct clk_oxnas_pllb *pllb = to_clk_oxnas_pllb(hw);
 
-	rstc = of_reset_control_get(node_pllb, NULL);
-	if (IS_ERR(rstc))
-		return PTR_ERR(rstc);
+	pllb->rstc = of_reset_control_get(pllb->devnode, NULL);
+
+	return IS_ERR(pllb->rstc) ? PTR_ERR(pllb->rstc) : 0;
+}
+
+static void pllb_clk_unprepare(struct clk_hw *hw)
+{
+	struct clk_oxnas_pllb *pllb = to_clk_oxnas_pllb(hw);
+
+	BUG_ON(IS_ERR(pllb->rstc));
+
+	reset_control_put(pllb->rstc);
+	pllb->rstc = NULL;
+}
+
+static int pllb_clk_enable(struct clk_hw *hw)
+{
+	struct clk_oxnas_pllb *pllb = to_clk_oxnas_pllb(hw);
+
+	BUG_ON(IS_ERR(pllb->rstc));
 
 	/* put PLL into bypass */
 	oxnas_register_set_mask(SEC_CTRL_PLLB_CTRL0, BIT(PLLB_BYPASS));
 	wmb();
 	udelay(10);
-	reset_control_assert(rstc);
+	reset_control_assert(pllb->rstc);
 	udelay(10);
 	/* set PLL B control information */
 	writel((1 << PLLB_ENSAT) | (1 << PLLB_OUTDIV) | (2 << PLLB_REFDIV),
 				SEC_CTRL_PLLB_CTRL0);
-	reset_control_deassert(rstc);
-	reset_control_put(rstc);
+	reset_control_deassert(pllb->rstc);
 	udelay(100);
 	oxnas_register_clear_mask(SEC_CTRL_PLLB_CTRL0, BIT(PLLB_BYPASS));
 
 	return 0;
 }
 
-void pllb_clk_disable(struct clk_hw *hw)
+static void pllb_clk_disable(struct clk_hw *hw)
 {
-	struct reset_control *rstc;
+	struct clk_oxnas_pllb *pllb = to_clk_oxnas_pllb(hw);
+
+	BUG_ON(IS_ERR(pllb->rstc));
 
 	/* put PLL into bypass */
 	oxnas_register_set_mask(SEC_CTRL_PLLB_CTRL0, BIT(PLLB_BYPASS));
 	wmb();
 	udelay(10);
 
-	rstc = of_reset_control_get(node_pllb, NULL);
-	if (!IS_ERR(rstc))
-		reset_control_assert(rstc);
+	reset_control_assert(pllb->rstc);
 }
 
 static struct clk_ops pllb_ops = {
+	.prepare = pllb_clk_prepare,
+	.unprepare = pllb_clk_unprepare,
+	.is_prepared = pllb_clk_is_prepared,
 	.enable = pllb_clk_enable,
 	.disable = pllb_clk_disable,
 };
@@ -120,9 +152,6 @@ static struct clk_init_data clk_pllb_init = {
 	.num_parents = ARRAY_SIZE(pll_clk_parents),
 };
 
-static struct clk_hw pllb_hw = {
-	.init = &clk_pllb_init,
-};
 
 /* standard gate clock */
 struct clk_std {
@@ -252,10 +281,16 @@ CLK_OF_DECLARE(oxnas_plla, "plxtech,nas782x-plla", oxnas_init_plla);
 void __init oxnas_init_pllb(struct device_node *np)
 {
 	struct clk *clk;
+	struct clk_oxnas_pllb *pllb;
+
+	pllb = kmalloc(sizeof(*pllb), GFP_KERNEL);
+	BUG_ON(!pllb);
 
-	node_pllb = np;
+	pllb->hw.init = &clk_pllb_init;
+	pllb->devnode = np;
+	pllb->rstc = NULL;
 
-	clk = clk_register(NULL, &pllb_hw);
+	clk = clk_register(NULL, &pllb->hw);
 	BUG_ON(IS_ERR(clk));
 	of_clk_add_provider(np, of_clk_src_simple_get, clk);
 }