From fff070f2cbb01b7c0879e9dcb13ee4e3ed2497f0 Mon Sep 17 00:00:00 2001
From: cinap_lenrek <cinap_lenrek@felloff.net>
Date: Sun, 8 May 2022 16:50:29 +0000
Subject: 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
---
 sys/src/9/imx8/uartimx.c | 383 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 383 insertions(+)
 create mode 100644 sys/src/9/imx8/uartimx.c

(limited to 'sys/src/9/imx8/uartimx.c')

diff --git a/sys/src/9/imx8/uartimx.c b/sys/src/9/imx8/uartimx.c
new file mode 100644
index 000000000..afc7d0096
--- /dev/null
+++ b/sys/src/9/imx8/uartimx.c
@@ -0,0 +1,383 @@
+#include "u.h"
+#include "../port/lib.h"
+#include "../port/error.h"
+#include "mem.h"
+#include "dat.h"
+#include "fns.h"
+#include "io.h"
+
+enum {
+	URXD	= 0x00/4,	/* UART Receiver Register */
+		RX_CHARRDY	= 1<<15,
+		RX_ERR		= 1<<14,
+		RX_OVRRUN	= 1<<13,
+		RX_FRMERR	= 1<<12,
+		RX_BRK		= 1<<11,
+		RX_PRERR	= 1<<10,
+		RX_DATA		= 0xFF,
+		
+	UTXD	= 0x40/4,	/* UART Transmitter Register */
+		TX_DATA		= 0xFF,
+
+	UCR1	= 0x80/4,	/* UART Control Register 1 */
+		CR1_ADEN	= 1<<15,	/* Automatic Baud Rate Detection Interrupt Enable */
+		CR1_ADNR	= 1<<14,	/* Automatic Detection of Baud Rate */
+		CR1_TRDYEN	= 1<<13,	/* Transmitter Ready Interrupt Enable */
+		CR1_IDEN	= 1<<12,	/* Idle Condition Detected Interrupt Enable */
+
+		CR1_ICD_SHIFT	= 10,		/* Idle Condition Detect Mask */
+		CR1_ICD_MASK	= 3<<CR1_ICD_SHIFT,
+
+		CR1_RRDYEN	= 1<<9,		/* Receiver Ready Interrupt Enable */
+		CR1_RXDMAEN	= 1<<8,		/* Receive Ready DMA Enable */
+		CR1_IREN	= 1<<7,		/* Infrared Interface Enable */
+		CR1_TXMPTYEN	= 1<<6,		/* Transmitter Empty Interrupt Enable */
+		CR1_RTSDEN	= 1<<5,		/* RTS Delta Interrupt Enable */
+		CR1_SNDBRK	= 1<<4,		/* Send BREAK */
+		CR1_TXDMAEN	= 1<<3,		/* Transmitter Ready DMA Enable */
+		CR1_ATDMAEN	= 1<<2,		/* Aging DMA Timer Enable */
+		CR1_DOZE	= 1<<1,		/* DOZE */
+		CR1_UARTEN	= 1<<0,		/* Uart Enable */
+
+	UCR2	= 0x84/4,	/* UART Control Register 2 */
+		CR2_ESCI	= 1<<15,	/* Escape Sequence Interrupt Enable */
+		CR2_IRTS	= 1<<14,	/* Ignore RTS Pin */
+		CR2_CTSC	= 1<<13,	/* CTS Pin Control */
+		CR2_CTS		= 1<<12,	/* Clear to Send */
+		CR2_ESCEN	= 1<<11,	/* Escape Enable */
+
+		CR2_RTEC_RAISING= 0<<9,
+		CR2_RTEC_FALLING= 1<<9,
+		CR2_RTEC_ANY	= 2<<9,
+		CR2_RTEC_MASK	= 3<<9,
+
+		CR2_PREN	= 1<<8,		/* Parity Enable */
+		CR2_PREVEN	= 0<<7,		/* Parity Even */
+		CR2_PRODD	= 1<<7,		/* Parity Odd */
+		CR2_STPB	= 1<<6,		/* Stop */
+		CR2_WS8		= 1<<5,		/* Word Size */
+		CR2_WS7		= 0<<5,
+		CR2_RTSEN	= 1<<4,		/* Request to Send Interrupt Enable */
+		CR2_ATEN	= 1<<3,		/* Aging Timer Enable */
+		CR2_TXEN	= 1<<2,		/* Transmitter Enable */
+		CR2_RXEN	= 1<<1,		/* Receiver Enable */
+		CR2_SRST	= 1<<0,		/* Software Reset */
+
+	UCR3	= 0x88/4,	/* UART Control Register 3 */
+		CR3_PARERREN	= 1<<12,	/* Parity Error Interrupt Enable */
+		CR3_FRAERREN	= 1<<11,	/* Frame Error Interrupt Enable */
+		CR3_ADNIMP	= 1<<7,		/* Autobaud Detection Not Improved */
+		CR3_RXDSEN	= 1<<6,		/* Receive Status Interrupt Enable */
+		CR3_AIRINTEN	= 1<<5,		/* Asynchronous IR WAKE Interrupt Enable */
+		CR3_AWAKEN	= 1<<4,		/* Asynchronous WAKE Interrupt Enable */
+		CR3_RXDMUXSEL	= 1<<2,		/* RXD Muxed Input Selected */
+		CR3_INVT	= 1<<1,		/* Invert TXD output in RS-232/RS-485 mode */
+		CR3_ACIEN	= 1<<0,		/* Autobaud Counter Interrupt Enable */
+
+	UCR4	= 0x8C/4,	/* UART Control Register 4 */
+		CR4_CTSTL_SHIFT	= 10,		/* CTS Trigger Level */
+		CR4_CTSTL_MASK	= 0x3F<<CR4_CTSTL_SHIFT,
+
+		CR4_INVR	= 1<<9,		/* Invert RXD Input in RS-232/RS-485 Mode */
+		CR4_ENIRI	= 1<<8,		/* Serial Infrared Interrupt Enable */
+		CR4_WKEN	= 1<<7,		/* WAKE Interrupt Enable */
+		CR4_IDDMAEN	= 1<<6,		/* DMA IDLE Condition Detected Interrupt Enable */
+		CR4_IRSC	= 1<<5,		/* IR Special Case */
+		CR4_LPBYP	= 1<<4,		/* Low Power Bypass */
+		CR4_TCEN	= 1<<3,		/* Transmit Complete Interrupt Enable */
+		CR4_BKEN	= 1<<2,		/* BREAK Condition Detected Interrupt Enable */
+		CR4_OREN	= 1<<1,		/* Receiver Overrun Interrupt Enable */
+		CR4_DREN	= 1<<0,		/* Receive Data Interrupt Enable */
+
+	UFCR	= 0x90/4,	/* UART FIFO Control Register */ 
+		FCR_TXTL_SHIFT	= 10,		/* Transmitter Trigger Level */
+		FCR_TXTL_MASK	= 0x3F<<FCR_TXTL_SHIFT,
+
+		FCR_RFDIV_SHIFT	= 7,		/* Reference Frequency Divider */
+		FCR_RFDIV_MASK	= 0x7<<FCR_RFDIV_SHIFT,
+
+		FCR_DCE		= 0<<6,		/* DCE/DTE mode select */
+		FCR_DTE		= 1<<6,
+
+		FCR_RXTL_SHIFT	= 0,		/* Receive Trigger Level */
+		FCR_RXTL_MASK	= 0x3F<<FCR_RXTL_SHIFT,
+
+	USR1	= 0x94/4,	/* UART Status Register 1 */
+		SR1_PARITYERR	= 1<<15,	/* Parity Error Interrupt Flag */
+		SR1_RTSS	= 1<<14,	/* RTS_B Pin Status */
+		SR1_TRDY	= 1<<13,	/* Transmitter Ready Interrupt / DMA Flag */
+		SR1_RTSD	= 1<<12,	/* RTS Delta */
+		SR1_ESCF	= 1<<11,	/* Escape Sequence Interrupt Flag */
+		SR1_FRAMEERR	= 1<<10,	/* Frame Error Interrupt Flag */
+		SR1_RRDY	= 1<<9,		/* Receiver Ready Interrupt / DMA Flag */
+		SR1_AGTIM	= 1<<8,		/* Aging Timer Interrupt Flag */
+		SR1_DTRD	= 1<<7,	
+		SR1_RXDS	= 1<<6,		/* Receiver IDLE Interrupt Flag */
+		SR1_AIRINT	= 1<<5,		/* Asynchronous IR WAKE Interrupt Flag */
+		SR1_AWAKE	= 1<<4,		/* Asynchronous WAKE Interrupt Flag */
+		SR1_SAD		= 1<<3,		/* RS-485 Slave Address Detected Interrupt Flag */
+
+	USR2	= 0x98/4,	/* UART Status Register 2 */
+		SR2_ADET	= 1<<15,	/* Automatic Baud Rate Detected Complete */
+		SR2_TXFE	= 1<<14,	/* Transmit Buffer FIFO Empty */
+		SR2_DTRF	= 1<<13,
+		SR2_IDLE	= 1<<12,	/* Idle Condition */
+		SR2_ACST	= 1<<11,	/* Autobaud Counter Stopped */
+		SR2_RIDELT	= 1<<10,
+		SR2_RIIN	= 1<<9,
+		SR2_IRINT	= 1<<8,		/* Serial Infrared Interrupt Flag */
+		SR2_WAKE	= 1<<7,		/* Wake */
+		SR2_DCDDELT	= 1<<6,
+		SR2_DCDIN	= 1<<5,
+		SR2_RTSF	= 1<<4,		/* RTS Edge Triggered Interrupt Flag */
+		SR2_TXDC	= 1<<3,		/* Transmitter Complete */
+		SR2_BRCD	= 1<<2,		/* BREAK Condition Detected */
+		SR2_ORE		= 1<<1,		/* Overrun Error */
+		SR2_RDR		= 1<<0,		/* Receive Data Ready */
+
+	UESC	= 0x9C/4,	/* UART Escape Character Register */
+	UTIM	= 0xA0/4,	/* UART Escape Timer Register */
+	UBIR	= 0xA4/4,	/* UART BRM Incremental Modulator Register */
+	UBMR	= 0xA8/4,	/* UART BRM Modulator Register */
+	UBRC	= 0xAC/4,	/* UART Baud Rate Count Register */
+	ONEMS	= 0xB0/4,	/* UART One-Millisecond Register */
+	UTS	= 0xB5/4,	/* UART Test Register */
+	UMCR	= 0xB8/4,	/* UART RS-485 Mode Control Register */
+};
+
+extern PhysUart imxphysuart;
+
+static Uart uart1 = {
+	.regs	= (u32int*)(VIRTIO + 0x860000ULL),
+	.name	= "uart1",
+	.baud	= 115200,
+	.freq	= 25*Mhz,
+	.phys	= &imxphysuart,
+};
+
+static Uart*
+pnp(void)
+{
+	return &uart1;
+}
+
+static void
+kick(Uart *u)
+{
+	u32int *regs = (u32int*)u->regs;
+
+	if(u->blocked)
+		return;
+	while(regs[USR1] & SR1_TRDY){
+		if(u->op >= u->oe && uartstageoutput(u) == 0)
+			break;
+		regs[UTXD] = *(u->op++) & TX_DATA;
+	}
+}
+
+static void
+config(Uart *u)
+{
+	u32int cr2, *regs = u->regs;
+
+	/* enable uart */
+	regs[UCR1] = CR1_UARTEN;
+
+	cr2 = CR2_SRST | CR2_IRTS | CR2_RXEN | CR2_TXEN;
+	switch(u->parity){
+	case 'e': cr2 |= CR2_PREN | CR2_PREVEN; break;
+	case 'o': cr2 |= CR2_PREN | CR2_PRODD; break;
+	}
+	cr2 |= u->bits == 7 ? CR2_WS7 : CR2_WS8;
+	if(u->stop == 2) cr2 |= CR2_STPB;
+	regs[UCR2] = cr2;
+	regs[UCR3] = 0x7<<8 | CR3_RXDMUXSEL;
+	regs[UCR4] = 31<<CR4_CTSTL_SHIFT;
+
+	/* baud = clock / (16 * (ubmr+1)/(ubir+1)) */
+	regs[UFCR] = (6 - 1)<<FCR_RFDIV_SHIFT | 32<<FCR_TXTL_SHIFT | 32<<FCR_RXTL_SHIFT;
+	regs[UBIR] = ((16*u->baud) / 1600)-1;
+	regs[UBMR] = (u->freq / 1600)-1;
+
+	regs[UCR1] = CR1_UARTEN | CR1_TRDYEN | CR1_RRDYEN;
+}
+
+static int
+bits(Uart *u, int n)
+{
+	switch(n){
+	case 8:
+		break;
+	case 7:
+		break;
+	default:
+		return -1;
+	}
+	u->bits = n;
+	config(u);
+	return 0;
+}
+
+static int
+stop(Uart *u, int n)
+{
+	switch(n){
+	case 1:
+		break;
+	case 2:
+		break;
+	default:
+		return -1;
+	}
+	u->stop = n;
+	config(u);
+	return 0;
+}
+
+static int
+parity(Uart *u, int n)
+{
+	switch(n){
+	case 'n':
+		break;
+	case 'e':
+		break;
+	case 'o':
+		break;
+	default:
+		return -1;
+	}
+	u->parity = n;
+	config(u);
+	return 0;
+}
+
+static int
+baud(Uart *u, int n)
+{
+	if(u->freq == 0 || n <= 0)
+		return -1;
+	u->baud = n;
+	config(u);
+	return 0;
+}
+
+static void
+rts(Uart*, int)
+{
+}
+
+static void
+dobreak(Uart*, int)
+{
+}
+
+static long
+status(Uart *uart, void *buf, long n, long offset)
+{
+	char *p;
+
+	p = malloc(READSTR);
+	if(p == nil)
+		error(Enomem);
+	snprint(p, READSTR,
+		"b%d\n"
+		"dev(%d) type(%d) framing(%d) overruns(%d) "
+		"berr(%d) serr(%d)\n",
+
+		uart->baud,
+		uart->dev,
+		uart->type,
+		uart->ferr,
+		uart->oerr,
+		uart->berr,
+		uart->serr
+	);
+	n = readstr(offset, buf, n, p);
+	free(p);
+
+	return n;
+}
+
+static void
+interrupt(Ureg*, void *arg)
+{
+	Uart *uart = arg;
+	u32int v, *regs = (u32int*)uart->regs;
+
+	while((v = regs[URXD]) & RX_CHARRDY)
+		uartrecv(uart, v & RX_DATA);
+
+	uartkick(uart);
+}
+
+static void
+disable(Uart *u)
+{
+	u32int *regs = u->regs;
+	regs[UCR1] = 0;
+}
+
+static void
+enable(Uart *u, int ie)
+{
+	disable(u);
+	if(ie) intrenable(IRQuart1, interrupt, u, BUSUNKNOWN, u->name);
+	config(u);
+}
+
+static void
+donothing(Uart*, int)
+{
+}
+
+static void
+putc(Uart *u, int c)
+{
+	u32int *regs = u->regs;
+
+	while((regs[USR1] & SR1_TRDY) == 0)
+		;
+	regs[UTXD] = c & TX_DATA;
+}
+
+static int
+getc(Uart *u)
+{
+	u32int c, *regs = (u32int*)u->regs;
+
+	do 
+		c = regs[URXD];
+	while((c & RX_CHARRDY) == 0);
+	return c & RX_DATA;
+}
+
+void
+uartconsinit(void)
+{
+	consuart = &uart1;
+	consuart->console = 1;
+	uartctl(consuart, "l8 pn s1");
+	uartputs(kmesg.buf, kmesg.n);
+}
+
+PhysUart imxphysuart = {
+	.name		= "imx",
+	.pnp		= pnp,
+	.enable		= enable,
+	.disable	= disable,
+	.kick		= kick,
+	.dobreak	= dobreak,
+	.baud		= baud,
+	.bits		= bits,
+	.stop		= stop,
+	.parity		= parity,
+	.modemctl	= donothing,
+	.rts		= rts,
+	.dtr		= donothing,
+	.status		= status,
+	.fifo		= donothing,
+	.getc		= getc,
+	.putc		= putc,
+};
+
-- 
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