imx8: add work in progress i.MX8MQ kernel for the mntreform2 laptop

This is a work in progress port to the mntreform2 laptop.

Working so far:

- mmu (same as raspberry pi 3b+)
- arm generic timer
- gicv3
- uart1
- enet

With access to the uart, one can netboot this kernel in u-boot
using the following commands:

> dhcp
> bootm

1 files changed, 218 insertions, 0 deletions

diff --git a/sys/src/9/imx8/main.c b/sys/src/9/imx8/main.c
new file mode 100644
index 000000000..6f9406564
--- /dev/null
+++ b/sys/src/9/imx8/main.c
@@ -0,0 +1,218 @@
+#include "u.h"
+#include "tos.h"
+#include "../port/lib.h"
+#include "mem.h"
+#include "dat.h"
+#include "fns.h"
+#include "../port/error.h"
+#include "pool.h"
+#include "io.h"
+#include "sysreg.h"
+
+Conf conf;
+
+/*
+ *  starting place for first process
+ */
+void
+init0(void)
+{
+	char **sp;
+
+	chandevinit();
+
+	if(!waserror()){
+		ksetenv("cputype", "arm64", 0);
+		if(cpuserver)
+			ksetenv("service", "cpu", 0);
+		else
+			ksetenv("service", "terminal", 0);
+		ksetenv("console", "0", 0);
+		poperror();
+	}
+	kproc("alarm", alarmkproc, 0);
+	sp = (char**)(USTKTOP-sizeof(Tos) - 8 - sizeof(sp[0])*4);
+	sp[3] = sp[2] = sp[1] = nil;
+	strcpy(sp[1] = (char*)&sp[4], "boot");
+	sp[0] = (void*)&sp[1];
+	touser((uintptr)sp);
+}
+
+void
+confinit(void)
+{
+	int userpcnt;
+	ulong kpages;
+	char *p;
+	int i;
+
+	conf.nmach = 1;
+
+	if(p = getconf("service")){
+		if(strcmp(p, "cpu") == 0)
+			cpuserver = 1;
+		else if(strcmp(p,"terminal") == 0)
+			cpuserver = 0;
+	}
+
+	if(p = getconf("*kernelpercent"))
+		userpcnt = 100 - strtol(p, 0, 0);
+	else
+		userpcnt = 0;
+
+	if(userpcnt < 10)
+		userpcnt = 60 + cpuserver*10;
+
+	conf.npage = 0;
+	for(i = 0; i < nelem(conf.mem); i++)
+		conf.npage += conf.mem[i].npage;
+
+	kpages = conf.npage - (conf.npage*userpcnt)/100;
+	if(kpages > ((uintptr)-VDRAM)/BY2PG)
+		kpages = ((uintptr)-VDRAM)/BY2PG;
+
+	conf.upages = conf.npage - kpages;
+	conf.ialloc = (kpages/2)*BY2PG;
+
+	/* set up other configuration parameters */
+	conf.nproc = 100 + ((conf.npage*BY2PG)/MB)*5;
+	if(cpuserver)
+		conf.nproc *= 3;
+	if(conf.nproc > 2000)
+		conf.nproc = 2000;
+	conf.nswap = conf.npage*3;
+	conf.nswppo = 4096;
+	conf.nimage = 200;
+
+	conf.copymode = conf.nmach > 1;
+
+	/*
+	 * Guess how much is taken by the large permanent
+	 * datastructures. Mntcache and Mntrpc are not accounted for.
+	 */
+	kpages = conf.npage - conf.upages;
+	kpages *= BY2PG;
+	kpages -= conf.upages*sizeof(Page)
+		+ conf.nproc*sizeof(Proc)
+		+ conf.nimage*sizeof(Image)
+		+ conf.nswap
+		+ conf.nswppo*sizeof(Page*);
+	mainmem->maxsize = kpages;
+	if(!cpuserver)
+		/*
+		 * give terminals lots of image memory, too; the dynamic
+		 * allocation will balance the load properly, hopefully.
+		 * be careful with 32-bit overflow.
+		 */
+		imagmem->maxsize = kpages;
+
+}
+
+void
+machinit(void)
+{
+	m->ticks = 1;
+	m->perf.period = 1;
+	active.machs[m->machno] = 1;
+}
+
+void
+main(void)
+{
+	machinit();
+	if(m->machno){
+		trapinit();
+		fpuinit();
+		intrinit();
+		clockinit();
+		// cpuidprint();
+		synccycles();
+		timersinit();
+		flushtlb();
+		mmu1init();
+		m->ticks = MACHP(0)->ticks;
+		schedinit();
+		return;
+	}
+	quotefmtinstall();
+	meminit();
+	confinit();
+	xinit();
+	uartconsinit();
+	printinit();
+	print("\nPlan 9\n");
+	trapinit();
+	fpuinit();
+	intrinit();
+	clockinit();
+	timersinit();
+	pageinit();
+	procinit0();
+	initseg();
+	links();
+	chandevreset();
+	userinit();
+//	mpinit();
+	mmu0clear((uintptr*)L1);
+	flushtlb();
+	mmu1init();
+	schedinit();
+}
+
+void
+exit(int)
+{
+	cpushutdown();
+	splfhi();
+	for(;;);
+}
+
+int
+isaconfig(char *, int, ISAConf *)
+{
+	return 0;
+}
+
+char*
+getconf(char *)
+{
+	return nil;
+}
+
+void
+writeconf(void)
+{
+}
+
+void
+reboot(void *, void *, ulong)
+{
+}
+
+void
+dmaflush(int clean, void *p, ulong len)
+{
+	uintptr s = (uintptr)p;
+	uintptr e = (uintptr)p + len;
+
+	if(clean){
+		s &= ~(BLOCKALIGN-1);
+		e += BLOCKALIGN-1;
+		e &= ~(BLOCKALIGN-1);
+		cachedwbse((void*)s, e - s);
+		return;
+	}
+	if(s & BLOCKALIGN-1){
+		s &= ~(BLOCKALIGN-1);
+		cachedwbinvse((void*)s, BLOCKALIGN);
+		s += BLOCKALIGN;
+	}
+	if(e & BLOCKALIGN-1){
+		e &= ~(BLOCKALIGN-1);
+		if(e < s)
+			return;
+		cachedwbinvse((void*)e, BLOCKALIGN);
+	}
+	if(s < e)
+		cachedinvse((void*)s, e - s);
+}