[+cc linux-arm, linux-samsung-soc, linux-serial] On Sun, Dec 9, 2012 at 11:25 PM, Woody Wu <narkewoody@xxxxxxxxx> wrote: > Hi, list > > I found some io memory information is lost from /dev/iomem and want to > find out why. > > I have a 2.6.16 kernel running on a ARM board (Samsung S3C2410). From > the kernel log, I see 16 8250 serial ports were detected, and each of > thoese ports has a memory address: > > Serial: 8250/16550 driver $Revision: 1.90 $ 16 ports, IRQ sharing enabled > serial8250: tts0 at MMIO 0xe1400000 (irq = 16) is a 16550A > serial8250: tts1 at MMIO 0xe1400008 (irq = 16) is a 16550A > serial8250: tts2 at MMIO 0xe1400010 (irq = 17) is a 16550A > serial8250: tts3 at MMIO 0xe1400018 (irq = 17) is a 16550A > serial8250: tts4 at MMIO 0xe1400020 (irq = 18) is a 16550A > serial8250: tts5 at MMIO 0xe1400028 (irq = 18) is a 16550A > serial8250: tts6 at MMIO 0xe1400030 (irq = 19) is a 16550A > serial8250: tts7 at MMIO 0xe1400038 (irq = 19) is a 16550A > serial8250: tts8 at MMIO 0xe1400040 (irq = 48) is a 16550A > serial8250: tts9 at MMIO 0xe1400048 (irq = 48) is a 16550A > serial8250: tts10 at MMIO 0xe1400050 (irq = 49) is a 16550A > serial8250: tts11 at MMIO 0xe1400058 (irq = 49) is a 16550A > serial8250: tts12 at MMIO 0xe1400060 (irq = 60) is a 16550A > serial8250: tts13 at MMIO 0xe1400068 (irq = 60) is a 16550A > serial8250: tts14 at MMIO 0xe1400070 (irq = 61) is a 16550A > serial8250: tts15 at MMIO 0xe1400078 (irq = 61) is a 16550A > > I can read/write these serial ports from /dev/ttys*, in other words, > they do exist. I also can find the driver info from /proc/devices: > > Character devices: > > ... > 4 /dev/vc/0 > 4 tty > 4 tts > 5 /dev/tty > 5 /dev/console > 5 /dev/ptmx > 7 vcs > ... > > The problem is, I don't understand why there is no information about > these ports in /proc/iomem file. The 'iomem' file now contains: > > 11000000-11000ffe : AX88796B > 19000000-19000ffe : AX88796B > 30000000-33ffffff : System RAM > 3001c000-301e826b : Kernel text > 301ea000-302234a3 : Kernel data > 49000000-490fffff : s3c2410-ohci > 49000000-490fffff : ohci_hcd > 4e000000-4e0fffff : s3c2410-nand > 4e000000-4e0fffff : s3c2410-nand > 50000000-50003fff : s3c2410-uart.0 > 50000000-500000ff : s3c2410-uart > 50004000-50007fff : s3c2410-uart.1 > 50004000-500040ff : s3c2410-uart > 50008000-5000bfff : s3c2410-uart.2 > 50008000-500080ff : s3c2410-uart > 53000000-530fffff : s3c2410-wdt > 54000000-540fffff : s3c2410-i2c > 5a000000-5a0fffff : s3c2410-sdi > 5a000000-5a0fffff : mmci-s3c2410 > > You see, there is no serial8250 informations. > > Can anyone here please tell me how this can happen? Does it mean the > serial8250 driver don't populate or register in the /proc/iomem? That looks like a bug to me. There should be entries in /proc/iomem for the hardware device (showing that something responds at that address) and for the driver that claims the device. I think the 8250 core does the reservation in serial8250_request_std_resource(). You could try putting some printks in that path to see whether it's exercised. You're running a fairly old kernel, so it's possible the bug has already been fixed. Bjorn -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
