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>
git-svn-id: svn://svn.openwrt.org/openwrt/trunk@43787 3c298f89-4303-0410-b956-a3cf2f4a3e73

diff --git a/target/linux/oxnas/files/drivers/clk/clk-oxnas.c b/target/linux/oxnas/files/drivers/clk/clk-oxnas.c
index 8d80c4f..00d0f7a 100644 (file)
--- a/target/linux/oxnas/files/drivers/clk/clk-oxnas.c
+++ b/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);
 }