Date: Sat, 22 Aug 2015 19:27:38 -0500 From: Karl Denninger <karl@denninger.net> To: freebsd-embedded@freebsd.org Subject: Re: spigen(4) SPI Generic IO interface -- need comments Message-ID: <55D9137A.4000403@denninger.net> In-Reply-To: <CAEv1%2BOXe4w8hJXQu2MsoMLz6ixeG3hU3BmLZpssG15SaPd9JGw@mail.gmail.com> References: <CAEv1%2BOU4cFpMpeQGfnCP7L4Q_k18rOSOA9JBnKUa99DS5dFnWA@mail.gmail.com> <20150817160423.GB3078@gmail.com> <CAEv1%2BOUhSAJxxWAfW2GUFVw=H-_KOs2dGg2d7uhZnFbqsHE5Qw@mail.gmail.com> <CAEv1%2BOXe4w8hJXQu2MsoMLz6ixeG3hU3BmLZpssG15SaPd9JGw@mail.gmail.com>
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This is a cryptographically signed message in MIME format. --------------ms060809040503060505040407 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: quoted-printable This is extremely cool stuff, and will make adding analog inputs to the Pi under FreeBSD easy..... which is exactly what I needed as a gating function for a project I wanted to undertake. On 8/22/2015 13:23, Brian Fundakowski Feldman wrote: > I've added a couple more features: > * clock adjustment via ioctl, independent per spigenN device > * mmap(2) support for very low latency > > On Tue, Aug 18, 2015 at 6:47 PM, Brian Fundakowski Feldman < > brianfundakowskifeldman@gmail.com> wrote: > >> On Mon, Aug 17, 2015 at 12:04 PM Tom Jones <jones@sdf.org> wrote: >> >>> On Mon, Aug 17, 2015 at 10:00:26AM -0400, Brian Fundakowski Feldman w= rote: >>>> I'm woefully out-of-practice with my kernel hackery (but still prett= y >>>> proficient in jiggery-pokery) so I would like to get comments on a >>> little >>>> driver I just made for interfacing arbitrarily in userland with SPI >>>> components. The only thing I'm exposing is a /dev/spigenN node with= a >>>> single transfer ioctl and I put together a test circuit and program >>> with an >>>> MCP3008 10-bit ADC IC to validate that it basically works, other tha= n >>> the >>>> limitation that the transfers must be octet-multiply-sized, but I >>> haven't >>>> looked at the SoC's (I'm using a Raspberry Pi 2) data sheet to tell >>> whether >>>> that's just a limit on the spibus(4) interface or the Broadcom SPI >>> driver >>>> or the Broadcom SoC itself. >>>> >>>> I hit one snag in development where I simply called the ioctl wrong = and >>>> found copyin(9) to page fault HARD if given a bogus user address to = copy >>>> from, and panic the kernel. I can post up the test program if anyon= e >>> wants >>>> but it's very trivial: I just align the start bit and the command da= ta >>> into >>>> the least significant bits of the first octet, shift it up two >>> positions so >>>> the NULs get clocked out as part of the command field, and provide t= wo >>>> octets for the data field to retrieve back the 10-bit digital value.= >>> Oh, cool. >>> >>> I did the same earlier this year, have you seen[1]?. >>> >>> The FreeBSD i2c api is the same/very similar the linux one[2][3]. Hav= e you >>> considered adding some of the ioctls[3] or the data structures to mak= e it >>> easier to port code? >>> >>> [1]: >>> https://lists.freebsd.org/pipermail/freebsd-embedded/2015-April/00246= 6.html >>> [2]: https://www.kernel.org/doc/Documentation/i2c/dev-interface >>> [3]: >>> https://www.freebsd.org/cgi/man.cgi?query=3Diic&apropos=3D0&sektion=3D= 0&manpath=3DFreeBSD+10.2-RELEASE&arch=3Ddefault&format=3Dhtml >>> [4]: https://www.kernel.org/doc/Documentation/spi/spidev >> >> I've iterated a bit on this to try to make some more sensible API, >> behaving reasonably about being able to set the SPI clock speed. I'm = going >> to implement an mmap handler so I can have my low-latency operation mo= de, >> as well. I don't like the Linux APIs one bit because it's just not sa= fe to >> allow all those configuration changes on a per-transfer basis... >> >> Moving this to -embedded because it's more apt than -hackers. >> >> >> >> _______________________________________________ >> freebsd-embedded@freebsd.org mailing list >> https://lists.freebsd.org/mailman/listinfo/freebsd-embedded >> To unsubscribe, send any mail to "freebsd-embedded-unsubscribe@freebsd= =2Eorg" --=20 Karl Denninger karl@denninger.net <mailto:karl@denninger.net> /The Market Ticker/ /[S/MIME encrypted email preferred]/ --------------ms060809040503060505040407 Content-Type: application/pkcs7-signature; name="smime.p7s" Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename="smime.p7s" Content-Description: S/MIME Cryptographic Signature MIAGCSqGSIb3DQEHAqCAMIACAQExCzAJBgUrDgMCGgUAMIAGCSqGSIb3DQEHAQAAoIIGXzCC BlswggRDoAMCAQICASkwDQYJKoZIhvcNAQELBQAwgZAxCzAJBgNVBAYTAlVTMRAwDgYDVQQI EwdGbG9yaWRhMRIwEAYDVQQHEwlOaWNldmlsbGUxGTAXBgNVBAoTEEN1ZGEgU3lzdGVtcyBM TEMxHDAaBgNVBAMTE0N1ZGEgU3lzdGVtcyBMTEMgQ0ExIjAgBgkqhkiG9w0BCQEWE0N1ZGEg U3lzdGVtcyBMTEMgQ0EwHhcNMTUwNDIxMDIyMTU5WhcNMjAwNDE5MDIyMTU5WjBaMQswCQYD VQQGEwJVUzEQMA4GA1UECBMHRmxvcmlkYTEZMBcGA1UEChMQQ3VkYSBTeXN0ZW1zIExMQzEe MBwGA1UEAxMVS2FybCBEZW5uaW5nZXIgKE9DU1ApMIICIjANBgkqhkiG9w0BAQEFAAOCAg8A MIICCgKCAgEAuYRY+EB2mGtZ3grlVO8TmnEvduVFA/IYXcCmNSOC1q+pTVjylsjcHKBcOPb9 TP1KLxdWP+Q1soSORGHlKw2/HcVzShDW5WPIKrvML+Ry0XvIvNBu9adTiCsA9nci4Cnf98XE hVpenER0qbJkBUOGT1rP4iAcfjet0lEgzPEnm+pAxv6fYSNp1WqIY9u0b1pkQiaWrt8hgNOc rJOiLbc8CeQ/DBP6rUiQjYNO9/aPNauEtHkNNfR9RgLSfGUdZuOCmJqnIla1HsrZhA5p69Bv /e832BKiNPaH5wF6btAiPpTr2sRhwQO8/IIxcRX1Vxd1yZbjYtJGw+9lwEcWRYAmoxkzKLPi S6Zo/6z5wgNpeK1H+zOioMoZIczgI8BlX1iHxqy/FAvm4PHPnC8s+BLnJLwr+jvMNHm82QwL J9hC5Ho8AnFU6TkCuq+P2V8/clJVqnBuvTUKhYMGSm4mUp+lAgR4L+lwIEqSeWVsxirIcE7Z OKkvI7k5x3WeE3+c6w74L6PfWVAd84xFlo9DKRdU9YbkFuFZPu21fi/LmE5brImB5P+jdqnK eWnVwRq+RBFLy4kehCzMXooitAwgP8l/JJa9VDiSyd/PAHaVGiat2vCdDh4b8cFL7SV6jPA4 k0MgGUA/6Et7wDmhZmCigggr9K6VQCx8jpKB3x1NlNNiaWECAwEAAaOB9DCB8TA3BggrBgEF BQcBAQQrMCkwJwYIKwYBBQUHMAGGG2h0dHA6Ly9jdWRhc3lzdGVtcy5uZXQ6ODg4ODAJBgNV HRMEAjAAMBEGCWCGSAGG+EIBAQQEAwIFoDALBgNVHQ8EBAMCBeAwLAYJYIZIAYb4QgENBB8W HU9wZW5TU0wgR2VuZXJhdGVkIENlcnRpZmljYXRlMB0GA1UdDgQWBBTFHJQt6cloXBdG1Pv1 o2YgH+7lWTAfBgNVHSMEGDAWgBQkcZudhX383d29sMqSlAOh+tNtNTAdBgNVHREEFjAUgRJr YXJsQGRlbm5pbmdlci5uZXQwDQYJKoZIhvcNAQELBQADggIBAE9/dxi2YqjCYYhiybp4GKcm 7tBVa/GLW+qcHPcoT4dqmqghlLz8+iUH+HCJjRQATVGyMEnvISOKFVHC6aZIG+Sg7J8bfS4+ fjKDi9smRH2VPPx3bV8+yFYRNroMGHaPHZB/Xctmmvc+PZ9O2W7rExgrODtxIOB3Zs6wkYf+ ty+9r1KmTHlV+rRHI6timH1uiyFE3cPi1taAEBxf0851cJV8k40PGF8G48ewnq8SY9sCf5cv liXbpdgU+I4ND5BuTjg63WS32zuhLd1VSuH3ZC/QbcncMX5W3oLXmcQP5/5uTiBJy74kdPtG MSZ9rXwZPwNxP/8PXMSR7ViaFvjUkf4bJlyENFa2PGxLk4EUzOuO7t3brjMlQW1fuInfG+ko 3tVxko20Hp0tKGPe/9cOxBVBZeZH/VgpZn3cLculGzZjmdh2fqAQ6kv9Z9AVOG1+dq0c1zt8 2zm+Oi1pikGXkfz5UJq60psY6zbX25BuEZkthO/qiS4pxjxb7gQkS0rTEHTy+qv0l3QVL0wa NAT74Zaj7l5DEW3qdQQ0dtVieyvptg9CxkfQJE3JyBMb0zBj9Qhc5/hbTfhSlHzZMEbUuIyx h9vxqFAmGzfB1/WfOKkiNHChkpPW8ZeH9yPeDBKvrgZ96dREHFoVkDk7Vpw5lSM+tFOfdyLg xxhb/RZVUDeUMYIE4zCCBN8CAQEwgZYwgZAxCzAJBgNVBAYTAlVTMRAwDgYDVQQIEwdGbG9y aWRhMRIwEAYDVQQHEwlOaWNldmlsbGUxGTAXBgNVBAoTEEN1ZGEgU3lzdGVtcyBMTEMxHDAa BgNVBAMTE0N1ZGEgU3lzdGVtcyBMTEMgQ0ExIjAgBgkqhkiG9w0BCQEWE0N1ZGEgU3lzdGVt cyBMTEMgQ0ECASkwCQYFKw4DAhoFAKCCAiEwGAYJKoZIhvcNAQkDMQsGCSqGSIb3DQEHATAc BgkqhkiG9w0BCQUxDxcNMTUwODIzMDAyNzM4WjAjBgkqhkiG9w0BCQQxFgQUlh+sWchUEFbp 6gO4+9EhOjRsvnYwbAYJKoZIhvcNAQkPMV8wXTALBglghkgBZQMEASowCwYJYIZIAWUDBAEC MAoGCCqGSIb3DQMHMA4GCCqGSIb3DQMCAgIAgDANBggqhkiG9w0DAgIBQDAHBgUrDgMCBzAN BggqhkiG9w0DAgIBKDCBpwYJKwYBBAGCNxAEMYGZMIGWMIGQMQswCQYDVQQGEwJVUzEQMA4G A1UECBMHRmxvcmlkYTESMBAGA1UEBxMJTmljZXZpbGxlMRkwFwYDVQQKExBDdWRhIFN5c3Rl bXMgTExDMRwwGgYDVQQDExNDdWRhIFN5c3RlbXMgTExDIENBMSIwIAYJKoZIhvcNAQkBFhND dWRhIFN5c3RlbXMgTExDIENBAgEpMIGpBgsqhkiG9w0BCRACCzGBmaCBljCBkDELMAkGA1UE BhMCVVMxEDAOBgNVBAgTB0Zsb3JpZGExEjAQBgNVBAcTCU5pY2V2aWxsZTEZMBcGA1UEChMQ Q3VkYSBTeXN0ZW1zIExMQzEcMBoGA1UEAxMTQ3VkYSBTeXN0ZW1zIExMQyBDQTEiMCAGCSqG SIb3DQEJARYTQ3VkYSBTeXN0ZW1zIExMQyBDQQIBKTANBgkqhkiG9w0BAQEFAASCAgB5vqQu sFCqGWwi+lCHmUtZyXLZusLqrUTVGT/pey3apv1Lr8ws4i7GqzZxMFNUWIZ3+Mx0va2YYhaV BmBOZZILTqpnBtcK/W4vJG4rq0nE3fY8JrzVLCwXJGaaQKVxkGMOj5dvLkFkVUB5hgTOfRjS HW7OiMEH+Ixpmua61SxOWGdyNLUI3SuTkzs7QpFa+RZi/RsNtGB3q5fI9e6AWTxX6bgYVLmk T3XlTxWtawyJF/UHTyi2wUaojYrJVa6QEi3Xr1oLUtmCOzrNQ/ddKR53JRpmW8/9SnkEwybl CmHY/Dp85vxZQlySPYQ4zk3r6o9/76Kxb9hFIUgPeO0D0lRn0v7eSKJCqJYYR3LVUlPbr+bn gGdtOsoXxpLwHbaAr2wIWVbIESxtGUbzFCu1rbFC1X91ttMzzchnI/1EuRUwGzf+prbMEYq+ iJGoaAlyRCqX3yzADEguJdn9UMI/KfF79WOWW60722NrXUgiV/XGHNq2PSVcmKc1swlO3M6T 7Go+a0FB34UV1VBmA2mlOejHoWxioMTbMx7HrF6RdABoXKFjtyHNlCZ4KKiTLQdk2Y68O8Kx umQCNlk3I7STntDAkQ1J0VuNJG7JUyMcTUIQsySn3617XM5oRFztAvVExZTByVZNJ3p1PqIp K19HGKRq3dD/TfFyBYPf0+afhbQqOgAAAAAAAA== --------------ms060809040503060505040407--
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