Date: Wed, 29 Aug 2018 23:40:58 +0200 From: Nicola Mingotti <nmingotti@gmail.com> To: Ian Lepore <ian@freebsd.org>, Russell Haley <russ.haley@gmail.com> Cc: freebsd-arm <freebsd-arm@freebsd.org>, Nicola Mingotti <nmingotti@gmail.com> Subject: Re: utility for pin in BBB: PX.Y --> pin_mode, pin_name Message-ID: <a2fe7129-054f-63dc-d6cd-d17288796b18@gmail.com> In-Reply-To: <1535576856.33841.58.camel@freebsd.org> References: <4661fc41-935a-56d5-2cc2-125085daf30a@gmail.com> <CABx9NuS%2B_HiUxReryc%2B5f7fYHq5OMK0FKBfEUWbRb88tOXjw7A@mail.gmail.com> <a9141acf-79dd-d702-ff35-d2a380f68e67@gmail.com> <1535568374.33841.47.camel@freebsd.org> <daef5dda-d180-03dc-19d9-263da42e39a8@gmail.com> <1535576856.33841.58.camel@freebsd.org>
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On 08/29/18 23:07, Ian Lepore wrote: > On Wed, 2018-08-29 at 22:26 +0200, Nicola Mingotti wrote: >> On 08/29/18 20:46, Ian Lepore wrote: >>> On Wed, 2018-08-29 at 20:01 +0200, Nicola Mingotti wrote: >>>> Thank you for suggestion Russel, >>>> >>>> but unfortunately, at best of my knowldege, >>>> $> man 3 gpio_open >>>> and its shell command brother >>>> $> man 8 gpioctl >>>> >>>> are not appropriate, they are useful only if a pin >>>> has been configured as GPIO pin. >>>> >>>> The program i look for would be useful instead to esablish >>>> which physical pin has been configured as GPIO pin or >>>> PWM, PRU, I2C etc. >>>> >>>> I asked also in the Forum, but the only one aswering >>>> (@Phishry) has given me your same suggestion. >>>> >>>> If nobody knows of such a program i will start the >>>> implementation, >>>> maybe >>>> tomorrow. >>>> >>>> bye >>>> Nicola >>>> >>> Please bottom-post when replying to freebsd mailing lists. >> ok ! >>> There is no interface defined for getting an fdt_pinctrl driver to >>> return info about the current configuration. Even if such an >>> interface >>> existed, there would also need to be a new driver providing a cdev >>> so >>> that userland can access the information. >> ok, no interface. >>> There is also nothing in freebsd equivelent to the linux devmem2 >>> program. A driver would have to be written to provide access to >>> device- >>> mapped memory before such a program could be written. You can't >>> access >>> arm hardware registers via /dev/mem or /dev/kmem. >>> >>> -- Ian >> I just compiled devmem2 and it seems to work. I did silly >> modifications. >> The code is here: http://euriscom.it/data/dm2.c >> (forget the first comment lines, they are poor, I did not intend to >> share this, it is my working copy) >> >> if i run it: >> --------------------------------- >> #> ./dm2 0x44e10998 b >> /dev/mem opened. >> Memory mapped at address 0x20221000. >> Value at address 0x44E10998 (0x20221998): 0x5 >> --------------------------------- >> >> Whic corresponds to what i wrote in the DTO. >> ----- >> pru_pru_pins: pinmux_pru_pru_pins { >> pinctrl-single,pins = < >> // 0x1a4 0x05 /* P9.27 >> pr1_pru0_pru_r30_5, >> Mode 5 output pull-down */ >> 0x19c 0x26 /* P9.28 pr1_pru0_pru_r31_3, >> Mode 6 input pull-down */ >> 0x198 0x05 /* PRU0-2 -- P9.30 -- >> pr1_pru0_pru_r30_2 ... se in MODE-5 */ >> >; >> }; >> ----- >> >> This is the only test i made but it seems improbable I got the same >> value by chance;) >> >> It goes without saying that I don't understand all what i wrote, >> so, i could be boldly wrong ;) >> >> If it turns out it works let me know, i can make the port. >> >> bye >> n. > You might accidentally get /dev/mem access to work, but it's not by > design. The rules of the arm memory model forbid mapping the same > physical memory to different virtual addresses using different > attributes (normal cacheable memory versus Device memory), and I don't > see anything in the arm devmem code that handles memory attributes. > > -- Ian I would like to discuss more this thing but really, i am too ignorant on this subject. What i can say is this, I learnt to use devmem2 from D.Molloy book "Exploring BeagleBone", see pg. 218. The author says this way "bypasses the Linux OS". I used the thing in Linux, it works, as it seems to do in FreeBSD-12-APLHA. If can tell you also I remember i used it one day in FreeBSD-11.1, it was working. I don't have the background to go deeper. If you can understand why it works and establish that it is realiable (even only for reading) let me (us) know ! ;) bye n. -- -------------------------- Dr. Nicola Mingotti R&D - Borghi Srl CTO - BondInsider --------------------------
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