ref: 733c5d6645b133b60d304c38fcb1398f94d0618c
dir: /sys/src/9/mt7688/i2c7688.c/
/* * I²C driver for MT7688 */ #include "u.h" #include "../port/lib.h" #include "../port/error.h" #include "mem.h" #include "dat.h" #include "fns.h" #include "io.h" #include "../port/i2c.h" enum { I²C_SM0CFG2 = 0x28, I²C_SM0CTL0 = 0x40, ctl0_strch = 1<<0, clt0_en = 1<<1, I²C_SM0CTL1 = 0x44, ctl1_trig = 1<<0, ctl1_start = 1<<4, ctl1_write = 2<<4, ctl1_stop = 3<<4, ctl1_rnack = 4<<4, ctl1_rack = 5<<4, I²C_SM0D0 = 0x50, I²C_SM0D1 = 0x54, }; #define ctl0_clkdiv(x) (((x) & 0x7FF) << 16) #define i2crd(o) (*IO(u32int, (I2CBASE + (o)))) #define i2cwr(o, v) (*IO(u32int, (I2CBASE + (o))) = (v)) int i2cdebug = 0; typedef struct Ctlr Ctlr; struct Ctlr { int clkdiv; }; static void reset(Ctlr *ctlr) { i2cwr(I²C_SM0CTL0, ctl0_strch | clt0_en | ctl0_clkdiv(ctlr->clkdiv)); i2cwr(I²C_SM0CFG2, 0x0); if(i2cdebug) print("i2c reset: %lux\n", i2crd(I²C_SM0CTL0)); } static int init(I2Cbus *bus) { Ctlr *ctlr = bus->ctlr; /* * Base clock on MT7688 is 40MHz * To get the standard speed for I²C of 100kHz, * 40MHz / 100kHz (and -1 to round up) */ ctlr->clkdiv = 40000000 / (bus->speed - 1); reset(ctlr); return 0; } static void i2cstop(void) { i2cwr(I²C_SM0CTL1, ctl1_stop | ctl1_trig); } static int i2cbusy(void) { u32int buf; int t; for(t = 0; t < 1000; t++){ buf = i2crd(I²C_SM0CTL1); if((buf & ctl1_trig) == 0){ return 0; } delay(1); } i2cstop(); return 1; } static int i2cstart(u32int flag, u32int bytes) { if(bytes > 0) bytes = bytes - 1; i2cwr(I²C_SM0CTL1, ctl1_trig | flag | bytes << 8); if(i2cbusy()){ return 1; } return 0; } static int i2cack(u32int bytes) { u32int buf, ack, expect; expect = (1 << bytes) - 1; buf = i2crd(I²C_SM0CTL1); ack = (buf >> 16) & 0xFF; if(i2cdebug) print("want; %d - got: %d - \n", expect, ack); if(ack == expect){ return 0; } i2cstop(); return 1; } static int io(I2Cdev *dev, uchar *pkt, int olen, int ilen) { int oΔ, iΔ, i, bytes; u16int addr, last; u32int data[2]; if(i2cdebug){ int alen = 1; if(olen > alen && (pkt[0] & 0xF8) == 0xF0) alen++; if(alen > 1){ addr = pkt[1] | (pkt[0] << 8); } else { addr = pkt[0]; } print("addr: %uX - ", addr>>1); } if(i2cbusy()){ print("I²C not ready\n"); return 0; } if(i2cstart(ctl1_start, 0)){ print("I²C no start\n"); return 0; } i = 0; oΔ = olen; iΔ = ilen; if(i2cdebug) print("total out: %d - in: %d - ", oΔ, iΔ); while(oΔ){ bytes = (oΔ >= 8) ? 8 : oΔ; data[0] = 0; data[1] = 0; memmove(data, &pkt[i], bytes); i2cwr(I²C_SM0D0, data[0]); i2cwr(I²C_SM0D1, data[1]); if(i2cstart(ctl1_write, bytes)){ print("I²C timeout\n"); return 0; } if(i2cack(bytes)){ if(i2cdebug) print("I²C write failed\n"); return 0; } i += bytes; oΔ -= bytes; } while(iΔ){ bytes = (iΔ >= 8) ? 8 : iΔ; data[0] = 0; data[1] = 0; last = (iΔ < 8) ? ctl1_rnack : ctl1_rack; if(i2cstart(last, bytes)){ print("I²C timeout\n"); return 0; } data[0] = i2crd(I²C_SM0D0); data[1] = i2crd(I²C_SM0D1); memmove(&pkt[i], data, bytes); if(last == ctl1_rack){ if(i2cack(bytes)){ if(i2cdebug) print("I²C read failed\n"); return 0; } } i += bytes; iΔ -= bytes; } if(i2cdebug) print("return: %d \n", i); i2cstop(); return i; } static Ctlr ctlr1; void i2c7688link(void) { static I2Cbus i2c1 = {"i2c1", 400000, &ctlr1, init, io}; addi2cbus(&i2c1); }