mtd: fsl-quadspi:fix qspi irq handler complete exception

In case of interrupt arrive immediately after requesting irq,
kernel will panic due to uninitialized variable.

Fix below exception:
Unable to handle kernel NULL pointer dereference
at virtual address 00000000
pgd = 80003000
[00000000] *pgd=80000080004003, *pmd=00000000
Internal error: Oops: 206 [#1] SMP THUMB2
Modules linked in:
CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.12.19-rt30+ #138
task: ef07c000 ti: ef080000 task.ti: ef080000
PC is at __swait_wake_locked+0x10/0x4e
LR is at complete+0x21/0x2e
pc : [<8002ee4a>]    lr : [<8002f2bb>]    psr: 400001b3
sp : ef081d00  ip : 0000001f  fp : ef080000
r10: 00000001  r9 : 00000000  r8 : 00000003
r7 : ef0329ac  r6 : 80000193  r5 : 00000000  r4 : ef0329ac
r3 : 00000000  r2 : 00000001  r1 : 00000003  r0 : ef0329ac
Flags: nZcv  IRQs off  FIQs on  Mode SVC_32  ISA Thumb  Segment kernel
Control: 70c53c7d  Table: 80003000  DAC: 02851004
Process swapper/0 (pid: 1, stack limit = 0xef080248)
Stack: (0xef081d00 to 0xef082000)
1d00: ef0329ac ef0329a8 80000193 ef081d20
      00000000 00000000 804c252c 8002f2bb
1d20: 80000000 804d6a13 ef3cc2c0 ef011c00
      000000a3 801c3c1d 801c3bdb 8003b8b7
1d40: ef011c00 ef3cc2c0 802e1ed0 00000000
      ef011c00 8049cd7c 00000000 ef081de4
1d60: 803f6b32 815115d0 804c252c 8003b9b9
      00000000 ef011c00 8049cd7c 8003d5cf
1d80: 000000a3 8003b3fb 000000a3 8000ca3d
      f0002000 ef081db0 804a8c8c 800083df
1da0: 802e1ed0 00000133 ffffffff 802e245b
      804fd8fc 60000113 00000066 00001dc5
1dc0: 804fd8fc 60000113 00000000 00000000
      803f6b32 815115d0 804c252c ef080000
1de0: 0000001f ef081df8 8023cb13 802e1ed0
      00000133 ffffffff ef032010 ef005e10
1e00: ef005e00 00000000 00000000 8023cb23
      f02c0000 801c4123 00000000 ef111280
1e20: ef032010 ef3caf40 ef3caf40 800b44ff
      ef07c000 00000000 ef3caf40 ef111300
1e40: ef269f80 800b4b37 804c256c 8023cce7
      ef063684 00000003 ef111300 00000000
1e60: 804fbbd4 ef005e10 00000000 ef005e10
      ef005e44 804fbbd4 804c2364 80482039
1e80: 000000ad 00000000 ef080000 80198371
      ef005e10 ef005e44 804c2364 00000000
1ea0: 80482039 801984a5 00000000 804c2364
      80198471 8019742d ef06365c ef110434
1ec0: 804c2364 804bfb30 ef269f80 80197e3b
      803f6bae 803f6bb3 00000071 804c2364
1ee0: 80490ad0 8049b374 804d6d40 8019882d
      00000000 00000006 80490ad0 800085f5
1f00: ef105300 ef105580 00000000 ef105580
      802ea500 803d4d54 00000000 800aeae1
1f20: 804ae908 00000113 80471461 815188d2
      815188da 80028f35 00000000 80447320
1f40: 00000000 000000ad 00000006 00000006
      00000001 00000006 80490ad0 8049b374
1f60: 804d6d40 804d6d40 000000ad 80490adc
      00000000 8047192d 00000006 00000006
1f80: 80471461 00000000 00000000 802db775
      00000000 00000000 00000000 00000000
1fa0: 00000000 802db77b 00000000 8000c219
      00000000 00000000 00000000 00000000
1fc0: 00000000 00000000 00000000 00000000
      00000000 00000000 00000000 00000000
1fe0: 00000000 00000000 00000000 00000000
      00000013 00000000 deadbeef deadbeef
[<8002ee4a>] (__swait_wake_locked+0x10/0x4e)
	     from [<8002f2bb>] (complete+0x21/0x2e)
[<8002f2bb>] (complete+0x21/0x2e)
	     from [<801c3c1d>] (fsl_qspi_irq_handler+0x43/0x46)
[<801c3c1d>] (fsl_qspi_irq_handler+0x43/0x46)
	     from [<8003b8b7>] (handle_irq_event_percpu+0x33/0x104)
[<8003b8b7>] (handle_irq_event_percpu+0x33/0x104)
	     from [<8003b9b9>] (handle_irq_event+0x31/0x48)
[<8003b9b9>] (handle_irq_event+0x31/0x48)
	     from [<8003d5cf>] (handle_fasteoi_irq+0x6b/0xa4)
[<8003d5cf>] (handle_fasteoi_irq+0x6b/0xa4)
	     from [<8003b3fb>] (generic_handle_irq+0x13/0x1c)
[<8003b3fb>] (generic_handle_irq+0x13/0x1c)
	     from [<8000ca3d>] (handle_IRQ+0x3d/0x60)
[<8000ca3d>] (handle_IRQ+0x3d/0x60)
	     from [<800083df>] (gic_handle_irq+0x2b/0x44)
[<800083df>] (gic_handle_irq+0x2b/0x44)
	     from [<802e245b>] (__irq_svc+0x3b/0x5c)
Exception stack(0xef081db0 to 0xef081df8)
1da0: 804fd8fc 60000113 00000066 00001dc5
1dc0: 804fd8fc 60000113 00000000 00000000
      803f6b32 815115d0 804c252c ef080000
1de0: 0000001f ef081df8 8023cb13 802e1ed0 00000133 ffffffff
[<802e245b>] (__irq_svc+0x3b/0x5c)
	     from [<802e1ed0>] (_raw_spin_unlock_irqrestore+0x16/0x18)
[<802e1ed0>] (_raw_spin_unlock_irqrestore+0x16/0x18)
	     from [<8023cb13>] (of_find_property+0x29/0x32)
[<8023cb13>] (of_find_property+0x29/0x32)
	     from [<8023cb23>] (of_get_property+0x7/0xc)
[<8023cb23>] (of_get_property+0x7/0xc)
	     from [<801c4123>] (fsl_qspi_probe+0x197/0x5b0)
[<801c4123>] (fsl_qspi_probe+0x197/0x5b0)
	     from [<80198371>] (driver_probe_device+0x65/0x140)
[<80198371>] (driver_probe_device+0x65/0x140)
	     from [<801984a5>] (__driver_attach+0x35/0x48)
[<801984a5>] (__driver_attach+0x35/0x48)
	     from [<8019742d>] (bus_for_each_dev+0x3b/0x46)
[<8019742d>] (bus_for_each_dev+0x3b/0x46)
	     from [<80197e3b>] (bus_add_driver+0x8b/0x164)
[<80197e3b>] (bus_add_driver+0x8b/0x164)
	     from [<8019882d>] (driver_register+0x4b/0x76)
[<8019882d>] (driver_register+0x4b/0x76)
	     from [<800085f5>] (do_one_initcall+0x65/0xd4)
[<800085f5>] (do_one_initcall+0x65/0xd4)
	     from [<8047192d>] (kernel_init_freeable+0xbd/0x150)
[<8047192d>] (kernel_init_freeable+0xbd/0x150)
	     from [<802db77b>] (kernel_init+0x7/0x90)
[<802db77b>] (kernel_init+0x7/0x90)
             from [<8000c219>] (ret_from_fork+0x11/0x38)
Code: 4607 4688 4692 46a9 (681e) 1f1c
---[ end trace 2857aa3b399c215c ]---
Kernel panic - not syncing: Fatal exception in interrupt
CPU1: stopping
CPU: 1 PID: 0 Comm: swapper/1 Tainted: G     D     3.12.19-rt30+ #138
[<80010829>] (unwind_backtrace+0x1/0x88)
	     from [<8000e53b>] (show_stack+0xb/0xc)
[<8000e53b>] (show_stack+0xb/0xc)
	     from [<802df461>] (dump_stack+0x4d/0x60)
[<802df461>] (dump_stack+0x4d/0x60)
	     from [<8000ff23>] (handle_IPI+0x7f/0xd0)
[<8000ff23>] (handle_IPI+0x7f/0xd0)
	     from [<800083ef>] (gic_handle_irq+0x3b/0x44)
[<800083ef>] (gic_handle_irq+0x3b/0x44)
	     from [<802e245b>] (__irq_svc+0x3b/0x5c)
Exception stack(0xef09bfa0 to 0xef09bfe8)
bfa0: ffffffed 00000000 01087000 00000000
      ef09a000 ef09a010 80000000 804d7054
bfc0: 80003010 410fc075 00000000 00000000
      00000008 ef09bfe8 8000cc21 8000cc22
bfe0: 60000133 ffffffff
[<802e245b>] (__irq_svc+0x3b/0x5c)
	     from [<8000cc22>] (arch_cpu_idle+0x1a/0x20)
[<8000cc22>] (arch_cpu_idle+0x1a/0x20)
	     from [<8003b395>] (cpu_startup_entry+0x7d/0xc4)
[<8003b395>] (cpu_startup_entry+0x7d/0xc4)
             from [<80008485>] (__enable_mmu+0x1/0x1c)

Signed-off-by: Haikun Wang <b53464@freescale.com>
Change-Id: If47a75274ae794a504cee0fca02920c9af1a29c1
Reviewed-on: http://git.am.freescale.net:8181/30121
Tested-by: Review Code-CDREVIEW <CDREVIEW@freescale.com>
Reviewed-by: Huan Wang <alison.wang@freescale.com>
Reviewed-by: Zhengxiong Jin <Jason.Jin@freescale.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/drivers/mtd/spi-nor/fsl-quadspi.c b/drivers/mtd/spi-nor/fsl-quadspi.c
index 2dd29c3..399c5e2 100644
--- a/drivers/mtd/spi-nor/fsl-quadspi.c
+++ b/drivers/mtd/spi-nor/fsl-quadspi.c
@@ -704,6 +704,10 @@ static int fsl_qspi_nor_setup(struct fsl_qspi *q)
 	qspi_writel(q, QUADSPI_MCR_RESERVED_MASK | QUADSPI_MCR_END_CFG_MASK,
 			base + QUADSPI_MCR);
 
+	/* clear flag register before enable the interrupt */
+	reg = qspi_readl(q, q->iobase + QUADSPI_FR);
+	qspi_writel(q, reg, q->iobase + QUADSPI_FR);
+
 	/* enable the interrupt */
 	qspi_writel(q, QUADSPI_RSER_TFIE, q->iobase + QUADSPI_RSER);
 
@@ -941,6 +945,10 @@ static int fsl_qspi_probe(struct platform_device *pdev)
 		goto irq_failed;
 	}
 
+	/* In case of interrupt arrive immediately after requesting irq,
+	 * kernel will panic without init_completion.
+	 */
+	init_completion(&q->c);
 	ret = devm_request_irq(dev, ret,
 			fsl_qspi_irq_handler, 0, pdev->name, q);
 	if (ret) {