imx8mm: Add spreadspectrum script as HACK for now

The script calculates register settings for the SSC in the VIDEO PLL
from modulation frequency and modulation range and writes it to the
register using devmem2.

BCS 746-000297

conf/machine/imx8mguf.conf

@@ -50,6 +50,7 @@ MACHINE_ESSENTIAL_EXTRA_RRECOMMENDS_append = " \
 	linux-firmware-imx-vpu \
 	rtl8723ds \
 	rtl8723ds-bt-uart-driver \
+	spreadspectrum \
 "
 
 DISTRO_EXTRA_RDEPENDS_remove = " \

recipes-guf/spreadspectrum/files/spreadspectrum.py

+#!/usr/bin/env python3
+# 
+#
+import sys
+import subprocess
+import argparse
+
+VIDEO_PLL1=0x30360000
+PLLBASE=VIDEO_PLL1
+
+FDIV_CTL0=0x2C
+FDIV_CTL1=0x30
+SSCG_CTRL=0x34
+
+verbose = 0
+def print_v1(*args, **kwargs):
+    if verbose < 1:
+        return
+    print(*args, file=sys.stderr, **kwargs)
+
+def print_v2(*args, **kwargs):
+    if verbose < 2:
+        return
+    print(*args, file=sys.stderr, **kwargs)
+
+def read_register(phyaddr):
+    cmd=['devmem2', "0x{:08x}".format(phyaddr)]
+    print_v2(cmd)
+    result=subprocess.run(cmd,capture_output=True)
+    out=result.stdout.decode('UTF-8')
+    lastline=out.splitlines()[-1]
+    value=int(lastline.split(' ')[-1], 0)
+    print_v2("0x{:08x}".format(value))
+    return(value)
+
+def write_register(phyaddr, value):
+    cmd=['devmem2', "0x{:08x}".format(phyaddr), 'w', "0x{:08x}".format(value) ]
+    print_v2(cmd)
+    result=subprocess.run(cmd,capture_output=True)
+    out=result.stdout.decode('UTF-8')
+    print_v2(out)
+    lastline=out.splitlines()[-1]
+    readbackvalue=int(lastline.split(' ')[-1], 0)
+    if readbackvalue != value:
+        raise Exception("Writing 0x{:08x} to 0x{:08x} failed.".format(value, phyaddr))
+
+def decode_ctl0(value):
+    pll_post_div = (value >>  0 ) & 0x007
+    pll_pre_div =  (value >>  4 ) & 0x03F
+    pll_main_div = (value >> 12 ) & 0x3FF
+    return pll_post_div,pll_pre_div,pll_main_div
+
+def decode_sscg(value):
+    sel_pf =        (value >>  0 ) & 0x003
+    pll_mrat_ctl =  (value >>  4 ) & 0x03F
+    pll_mfreq_ctl = (value >> 12 ) & 0x0FF
+    sscg_en =       (value >> 31 ) & 0x001
+    return sel_pf, pll_mrat_ctl, pll_mfreq_ctl, sscg_en
+
+def encode_sscg(sel_pf, pll_mrat_ctl, pll_mfreq_ctl, sscg_en):
+    s=sel_pf & 0x003
+    if s != sel_pf:
+        raise Exception("Value of sel_pf out of range ({})".format(sel_pf))
+    print_v2("Set sel_pf: {}".format(s))
+
+    pll_mrat_ctl = int(pll_mrat_ctl)
+    r=pll_mrat_ctl & 0x03F
+    if r != pll_mrat_ctl:
+        raise Exception("Value of pll_mrat_ctl out of range ({})".format(pll_mrat_ctl))
+    print_v2("Set pll_mrat_ctl: {}".format(r))
+
+    pll_mfreq_ctl = int(pll_mfreq_ctl)
+    f=pll_mfreq_ctl & 0x0FF
+    if f != pll_mfreq_ctl:
+        raise Exception("Value of pll_mfreq_ctl out of range ({})".format(pll_mfreq_ctl))
+    print_v2("Set pll_mfreq_ctl: {}".format(f))
+
+    e=sscg_en & 0x001
+    if e != sscg_en:
+        raise Exception("Value of sscg_en out of range ({})".format(sscg_en))
+    print_v2("Set sscg_en: {}".format(e))
+
+    value=s << 0 | r << 4 | f << 12 | e << 31
+    print_v1("Set register to : 0x{:08x}".format(value))
+
+    return value
+
+def main(args):
+    global verbose
+    parser = argparse.ArgumentParser(description=__doc__, usage="%(prog)s [OPTIONS]")
+
+    parser.add_argument(
+        "mode",
+        nargs='?',
+        action="store",
+        default='get',
+        type=str,
+        choices=['set','get','disable'],
+        help=("Use set the specify a new spreadspectrum setting, disable to disalbe spreadspectrum clocking."),
+    )
+    parser.add_argument(
+        "mfreq",
+        nargs='?',
+        action="store",
+        default=0,
+        type=float,
+        help=("Modulation frequency used for ssc [HZ]."),
+    )
+    parser.add_argument(
+        "mrate",
+        nargs='?',
+        action="store",
+        default=0,
+        type=float,
+        help=("Modulation rate used for ssc [%%]."),
+    )
+    parser.add_argument(
+        "-m",
+        "--method",
+        action="store",
+        dest="method",
+        default='center',
+        type=str,
+        choices=['down','up','center'],
+        help=("Define if the where to spread the spectrum."),
+    )
+    parser.add_argument(
+        "-v",
+        "--verbose",
+        action="count",
+        dest="verbose",
+        default=0,
+        help=("Increase verbosity."),
+    )
+    options = parser.parse_args(args)
+    verbose = options.verbose
+
+    if ( options.mode == 'disable' or 
+            ( options.mode == 'set' and ( options.mfreq == 0 or options.mrate == 0 ))):
+        print("Disable Spread spectrum ")
+        write_register(PLLBASE + SSCG_CTRL, encode_sscg( 0, 0, 0, 0))
+        exit(0)
+
+    pll_post_div,pll_pre_div,pll_main_div = decode_ctl0(read_register(PLLBASE + FDIV_CTL0))
+    print_v1("Post Div: {}\nPre Div: {}\nMain Div: {}".format(
+        pll_post_div,pll_pre_div,pll_main_div))
+
+    m=pll_main_div
+    p=pll_pre_div
+    Fin=24 * pow(10,6)
+
+    if options.mode == 'set':
+        MF=options.mfreq
+        print_v2("Target mfreq {}Hz".format(MF))
+        MR=options.mrate / 100
+        print_v2("Target mrate {}%".format(MR * 100))
+
+        mfr=Fin/p/MF/pow(2,5)
+        mrr=MR/(mfr/100/pow(2,6))
+        if options.method == 'center':
+            sel_pf = 0x2
+        elif options.method == 'down':
+            sel_pf = 0x0
+        elif options.method == 'up':
+            sel_pf = 0x1
+        else:
+            raise Exeption("Specify a valid value for --method")
+
+        try:
+            value=encode_sscg( sel_pf, mrr, mfr, 1)
+        except Exception as e:
+            print("Error: ", e.args)
+            exit(1)
+        write_register(PLLBASE + SSCG_CTRL, value )
+
+
+    # Allways
+    #if options.mode == 'get':
+    sel_pf, pll_mrat_ctl, pll_mfreq_ctl, sscg_en = decode_sscg(read_register(PLLBASE + SSCG_CTRL))
+    print_v1("Sel PF: {}\nPLL Mrat: {}\nPLL MFreq: {}\nSSCG_EN: {}".format(
+    sel_pf, pll_mrat_ctl, pll_mfreq_ctl, sscg_en))
+
+    if 0 == sscg_en:
+        print("Spread spectrum disabled")
+        exit(0)
+
+    mfr=pll_mfreq_ctl
+    mrr=pll_mrat_ctl
+    
+    MF=Fin/p/mfr/pow(2,5)
+    MR=mfr*mrr/100/pow(2,6)
+    if (sel_pf & 0x2) == 0x2:
+        method = 'center'
+    elif sel_pf == 0x0:
+        method = 'down'
+    elif sel_pf == 0x1:
+        method = 'up'
+    else:
+        method = 'unknown'
+            
+    print("Modulation frequency: {:.2f}Hz".format(MF))
+    print("Modulation range pk-pk: {}%".format(MR*100))
+    print("Modulation mode: {}".format(method))
+
+
+if __name__ == "__main__":
+    main(sys.argv[1:])
+
+

recipes-guf/spreadspectrum/files/spreadspectrum.service

+[Unit]
+Description=Apply spread spectrum settings
+Before=basic.target
+After=local-fs-pre.target
+DefaultDependencies=no
+
+[Service]
+Type=oneshot
+ExecStart=/bin/sh -c '/sbin/spreadspectrum.py set 30000 2'
+
+[Install]
+WantedBy=basic.target
+

recipes-guf/spreadspectrum/spreadspectrum.bb

+SUMMARY = "Garz & Fricke platform spreadspectrum script, HACK until driver is running."
+HOMEPAGE = "https://garz-fricke.com"
+
+LICENSE = "Apache-2.0"
+LIC_FILES_CHKSUM = "file://${COMMON_LICENSE_DIR}/Apache-2.0;md5=89aea4e17d99a7cacdbeed46a0096b10"
+
+SRC_URI = "file://spreadspectrum.py \
+           file://spreadspectrum.service"
+
+RDEPENDS_${PN} = " python3 devmem2 "
+
+COMPATIBLE_MACHINE = "mx8"
+
+S = "${WORKDIR}"
+
+do_install() {
+	install -d ${D}/sbin
+	install -m 0700 ${S}/spreadspectrum.py ${D}/sbin/spreadspectrum.py
+	install -d ${D}${systemd_system_unitdir}/
+	install -D -p -m0644 ${WORKDIR}/spreadspectrum.service ${D}${systemd_system_unitdir}/spreadspectrum.service
+}
+
+inherit systemd
+SYSTEMD_AUTO_ENABLE_${PN} = "enable"
+SYSTEMD_SERVICE_${PN} = "spreadspectrum.service"
+SYSTEMD_PACKAGES =+ "${PN}"
+
+FILES_${PN} = " \
+	sbin/spreadspectrum.py \
+	${systemd_system_unitdir}/spreadspectrum.service \
+	"