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Re: [Ltib] simple PWM driver for LPC3250

From: Li Yuan-Lung
Subject: Re: [Ltib] simple PWM driver for LPC3250
Date: Fri, 10 Sep 2010 13:15:55 +0800

Dear Giri,
Thank you for replying.
After fix the access method by ioremap(). The PWM works normally.

Here is my question:
Why the LPC32XX_CLKPWR_PWM_CLK_CTRL doesn't need to process by ioremap()?
Is it statically map by kernel? Where can I find the relate code in kernel source?
Thank you very much.


2010/9/9 Bangaragiri G <address@hidden>



  The LPC32XX_PWM1_BASE &  LPC32XX_PWM2_BASE  addresses are physical addresses, not kernel virtual addresses.

  Can you please ioremp these addresses in your driver & try again?





Bangaragiri G

E-mail: address@hidden



From: [] On Behalf Of Li Yuan-Lung
Sent: 2010 Sep 09 2:46 PM
To: Kevin Wells
Cc: address@hidden
Subject: [Ltib] simple PWM driver for LPC3250


Dear NXP guys,

I am trying to implement the simple PWM driver for LPC3250 under linux kernel 2.6.34.

Now I am stuck at the register writing. It's seems the Simple-PWM 1 and 2 were not functional.

Using raw_readl and raw_writel to the LPC32XX_CLKPWR_PWM_CLK_CTRL register is work, but which causes segmentation fault to the LPC32XX_PWM1_BASE and LPC32XX_PWM2_BASE.


Please kindly reply to me with some suggestion, thank you.


Here is my partial code in driver module:

//HW init first

tmp = __raw_readl(LPC32XX_CLKPWR_PWM_CLK_CTRL);

printk(KERN_ERR PWM_DRVNAME ": PWM clk reg value 0x%x\n", tmp);





__raw_writel(tmp, LPC32XX_CLKPWR_PWM_CLK_CTRL);//Turn On PWM1 and PWM2


tmp = __raw_readl(LPC32XX_CLKPWR_PWM_CLK_CTRL);

printk(KERN_ERR PWM_DRVNAME ": PWM clk reg value = 0x%x after write.\n", tmp);


tmp = LPC32XX_PWM1_EN | LPC32XX_PWM1_DUTY(127) | LPC32XX_PWM1_RELOADV(10);// 13M/10/256 = 5k

__raw_writel(tmp, LPC32XX_PWM1_BASE);

tmp = LPC32XX_PWM2_EN | LPC32XX_PWM2_DUTY(127) | LPC32XX_PWM2_RELOADV(10);

__raw_writel(tmp, LPC32XX_PWM2_BASE);


tmp = __raw_readl(LPC32XX_PWM1_BASE);

printk(KERN_ERR PWM_DRVNAME ": PWM1 reg value = 0x%x.\n", tmp);

tmp = __raw_readl(LPC32XX_PWM2_BASE);

printk(KERN_ERR PWM_DRVNAME ": PWM2 reg value = 0x%x.\n", tmp);


The result:

# insmod pwm.ko

pwmd: PWM clk reg value 0x0

pwmd: PWM clk reg value = 0x11f after write.

Unable to handle kernel paging request at virtual address 4005c000

pgd = c3d78000

[4005c000] *pgd=00000000

Internal error: Oops: 805 [#1] PREEMPT

last sysfs file:

Modules linked in: pwm(+)

CPU: 0    Not tainted  (2.6.34 #21)

PC is at pwm_init+0x40/0xdc [pwm]

LR is at schedule+0x2cc/0x34c

pc : [<bf0002d8>]    lr : [<c028ace8>]    psr: 60000013

sp : c3dcff20  ip : c3dcfe40  fp : c3dcff3c

r10: 00000000  r9 : c3dce000  r8 : 00000000

r7 : bf000298  r6 : c0365c6c  r5 : 4005c000  r4 : f4004000

r3 : 80000a7f  r2 : 00000000  r1 : 00000000  r0 : bf0004e0

Flags: nZCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment user

Control: 0005317f  Table: 83d78000  DAC: 00000015

Process insmod (pid: 393, stack limit = 0xc3dce270)

Stack: (0xc3dcff20 to 0xc3dd0000)

ff20: 0000001d 0000001d 00000000 bf0005c4 c3dcff7c c3dcff40 c00253a8 bf0002a8

ff40: 00011585 bf0005c4 00000000 001361b0 c0026068 00000000 c3dcff7c 00000000

ff60: bf0005c4 00000000 001361b0 c0026068 c3dcffa4 c3dcff80 c00717e8 c0025358

ff80: c00a4654 c00a3048 00000000 00000000 00000000 00000080 00000000 c3dcffa8

ffa0: c0025ec0 c0071730 00000000 00000000 001361b0 00011585 00135fd8 00000000

ffc0: 00000000 00000000 00000000 00000080 00135fc0 00000040 00135fa8 bea0de94

ffe0: bea0d740 bea0d730 000a7e10 000093c0 a0000010 001361b0 80421031 80421431


[<bf000298>] (pwm_init+0x0/0xdc [pwm]) from [<c00253a8>] (do_one_initcall+0x60/0x1ac)

 r5:bf0005c4 r4:00000000

[<c0025348>] (do_one_initcall+0x0/0x1ac) from [<c00717e8>] (sys_init_module+0xc8/0x1f8)

 r8:c0026068 r7:001361b0 r6:00000000 r5:bf0005c4 r4:00000000

[<c0071720>] (sys_init_module+0x0/0x1f8) from [<c0025ec0>] (ret_fast_syscall+0x0/0x2c)

 r7:00000080 r6:00000000 r5:00000000 r4:00000000

Code: eb411323 e59f5080 e59f3080 e59f0080 (e5853000)

---[ end trace 2fda102ac79baf84 ]---

Segmentation fault

Best Regards,

Henry Li
SW Engineer of Climax Co.
TEL: +886-2-2794-0001 ext.231
FAX: +886-2-2792-6618

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