ppc4xx_i2c: Implement basic I2C functions

Enough to please U-Boot and make it able to detect SDRAM SPD EEPROMs

Signed-off-by: François Revol <revol@free.fr>
Signed-off-by: BALATON Zoltan <balaton@eik.bme.hu>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

1 files changed, 168 insertions, 30 deletions

diff --git a/hw/i2c/ppc4xx_i2c.c b/hw/i2c/ppc4xx_i2c.c
index 5a6bde9..e873a44 100644
--- a/hw/i2c/ppc4xx_i2c.c
+++ b/hw/i2c/ppc4xx_i2c.c
@@ -2,6 +2,8 @@
  * PPC4xx I2C controller emulation
  *
  * Copyright (c) 2007 Jocelyn Mayer
+ * Copyright (c) 2012 François Revol
+ * Copyright (c) 2016 BALATON Zoltan
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -25,26 +27,118 @@
 #include "qemu/osdep.h"
 #include "qapi/error.h"
 #include "qemu-common.h"
+#include "qemu/log.h"
 #include "cpu.h"
 #include "hw/hw.h"
 #include "hw/i2c/ppc4xx_i2c.h"
 
-/*#define DEBUG_I2C*/
+#define PPC4xx_I2C_MEM_SIZE 0x12
 
-#define PPC4xx_I2C_MEM_SIZE 0x11
+#define IIC_CNTL_PT         (1 << 0)
+#define IIC_CNTL_READ       (1 << 1)
+#define IIC_CNTL_CHT        (1 << 2)
+#define IIC_CNTL_RPST       (1 << 3)
+
+#define IIC_STS_PT          (1 << 0)
+#define IIC_STS_ERR         (1 << 2)
+#define IIC_STS_MDBS        (1 << 5)
+
+#define IIC_EXTSTS_XFRA     (1 << 0)
+
+#define IIC_XTCNTLSS_SRST   (1 << 0)
+
+static void ppc4xx_i2c_reset(DeviceState *s)
+{
+    PPC4xxI2CState *i2c = PPC4xx_I2C(s);
+
+    /* FIXME: Should also reset bus?
+     *if (s->address != ADDR_RESET) {
+     *    i2c_end_transfer(s->bus);
+     *}
+     */
+
+    i2c->mdata = 0;
+    i2c->lmadr = 0;
+    i2c->hmadr = 0;
+    i2c->cntl = 0;
+    i2c->mdcntl = 0;
+    i2c->sts = 0;
+    i2c->extsts = 0x8f;
+    i2c->sdata = 0;
+    i2c->lsadr = 0;
+    i2c->hsadr = 0;
+    i2c->clkdiv = 0;
+    i2c->intrmsk = 0;
+    i2c->xfrcnt = 0;
+    i2c->xtcntlss = 0;
+    i2c->directcntl = 0x0f;
+    i2c->intr = 0;
+}
+
+static inline bool ppc4xx_i2c_is_master(PPC4xxI2CState *i2c)
+{
+    return true;
+}
 
 static uint64_t ppc4xx_i2c_readb(void *opaque, hwaddr addr, unsigned int size)
 {
     PPC4xxI2CState *i2c = PPC4xx_I2C(opaque);
     uint64_t ret;
 
-#ifdef DEBUG_I2C
-    printf("%s: addr " TARGET_FMT_plx "\n", __func__, addr);
-#endif
     switch (addr) {
     case 0x00:
-        /*i2c_readbyte(&i2c->mdata);*/
         ret = i2c->mdata;
+        if (ppc4xx_i2c_is_master(i2c)) {
+            ret = 0xff;
+
+            if (!(i2c->sts & IIC_STS_MDBS)) {
+                qemu_log_mask(LOG_GUEST_ERROR, "[%s]%s: Trying to read "
+                              "without starting transfer\n",
+                              TYPE_PPC4xx_I2C, __func__);
+            } else {
+                int pending = (i2c->cntl >> 4) & 3;
+
+                /* get the next byte */
+                int byte = i2c_recv(i2c->bus);
+
+                if (byte < 0) {
+                    qemu_log_mask(LOG_GUEST_ERROR, "[%s]%s: read failed "
+                                  "for device 0x%02x\n", TYPE_PPC4xx_I2C,
+                                  __func__, i2c->lmadr);
+                    ret = 0xff;
+                } else {
+                    ret = byte;
+                    /* Raise interrupt if enabled */
+                    /*ppc4xx_i2c_raise_interrupt(i2c)*/;
+                }
+
+                if (!pending) {
+                    i2c->sts &= ~IIC_STS_MDBS;
+                    /*i2c_end_transfer(i2c->bus);*/
+                /*} else if (i2c->cntl & (IIC_CNTL_RPST | IIC_CNTL_CHT)) {*/
+                } else if (pending) {
+                    /* current smbus implementation doesn't like
+                       multibyte xfer repeated start */
+                    i2c_end_transfer(i2c->bus);
+                    if (i2c_start_transfer(i2c->bus, i2c->lmadr >> 1, 1)) {
+                        /* if non zero is returned, the adress is not valid */
+                        i2c->sts &= ~IIC_STS_PT;
+                        i2c->sts |= IIC_STS_ERR;
+                        i2c->extsts |= IIC_EXTSTS_XFRA;
+                    } else {
+                        /*i2c->sts |= IIC_STS_PT;*/
+                        i2c->sts |= IIC_STS_MDBS;
+                        i2c->sts &= ~IIC_STS_ERR;
+                        i2c->extsts = 0;
+                    }
+                }
+                pending--;
+                i2c->cntl = (i2c->cntl & 0xcf) | (pending << 4);
+            }
+        } else {
+            qemu_log_mask(LOG_UNIMP, "[%s]%s: slave mode not implemented\n",
+                          TYPE_PPC4xx_I2C, __func__);
+        }
         break;
     case 0x02:
         ret = i2c->sdata;
@@ -88,13 +182,15 @@ static uint64_t ppc4xx_i2c_readb(void *opaque, hwaddr addr, unsigned int size)
     case 0x10:
         ret = i2c->directcntl;
         break;
+    case 0x11:
+        ret = i2c->intr;
+        break;
     default:
-        ret = 0x00;
+        qemu_log_mask(LOG_GUEST_ERROR, "[%s]%s: Bad address at offset 0x%"
+                      HWADDR_PRIx "\n", TYPE_PPC4xx_I2C, __func__, addr);
+        ret = 0;
         break;
     }
-#ifdef DEBUG_I2C
-    printf("%s: addr " TARGET_FMT_plx " %02" PRIx64 "\n", __func__, addr, ret);
-#endif
 
     return ret;
 }
@@ -103,26 +199,70 @@ static void ppc4xx_i2c_writeb(void *opaque, hwaddr addr, uint64_t value,
                               unsigned int size)
 {
     PPC4xxI2CState *i2c = opaque;
-#ifdef DEBUG_I2C
-    printf("%s: addr " TARGET_FMT_plx " val %08" PRIx64 "\n",
-           __func__, addr, value);
-#endif
+
     switch (addr) {
     case 0x00:
         i2c->mdata = value;
-        /*i2c_sendbyte(&i2c->mdata);*/
+        if (!i2c_bus_busy(i2c->bus)) {
+            /* assume we start a write transfer */
+            if (i2c_start_transfer(i2c->bus, i2c->lmadr >> 1, 0)) {
+                /* if non zero is returned, the adress is not valid */
+                i2c->sts &= ~IIC_STS_PT;
+                i2c->sts |= IIC_STS_ERR;
+                i2c->extsts |= IIC_EXTSTS_XFRA;
+            } else {
+                i2c->sts |= IIC_STS_PT;
+                i2c->sts &= ~IIC_STS_ERR;
+                i2c->extsts = 0;
+            }
+        }
+        if (i2c_bus_busy(i2c->bus)) {
+            if (i2c_send(i2c->bus, i2c->mdata)) {
+                /* if the target return non zero then end the transfer */
+                i2c->sts &= ~IIC_STS_PT;
+                i2c->sts |= IIC_STS_ERR;
+                i2c->extsts |= IIC_EXTSTS_XFRA;
+                i2c_end_transfer(i2c->bus);
+            }
+        }
         break;
     case 0x02:
         i2c->sdata = value;
         break;
     case 0x04:
         i2c->lmadr = value;
+        if (i2c_bus_busy(i2c->bus)) {
+            i2c_end_transfer(i2c->bus);
+        }
         break;
     case 0x05:
         i2c->hmadr = value;
         break;
     case 0x06:
         i2c->cntl = value;
+        if (i2c->cntl & IIC_CNTL_PT) {
+            if (i2c->cntl & IIC_CNTL_READ) {
+                if (i2c_bus_busy(i2c->bus)) {
+                    /* end previous transfer */
+                    i2c->sts &= ~IIC_STS_PT;
+                    i2c_end_transfer(i2c->bus);
+                }
+                if (i2c_start_transfer(i2c->bus, i2c->lmadr >> 1, 1)) {
+                    /* if non zero is returned, the adress is not valid */
+                    i2c->sts &= ~IIC_STS_PT;
+                    i2c->sts |= IIC_STS_ERR;
+                    i2c->extsts |= IIC_EXTSTS_XFRA;
+                } else {
+                    /*i2c->sts |= IIC_STS_PT;*/
+                    i2c->sts |= IIC_STS_MDBS;
+                    i2c->sts &= ~IIC_STS_ERR;
+                    i2c->extsts = 0;
+                }
+            } else {
+                /* we actually already did the write transfer... */
+                i2c->sts &= ~IIC_STS_PT;
+            }
+        }
         break;
     case 0x07:
         i2c->mdcntl = value & 0xDF;
@@ -135,6 +275,7 @@ static void ppc4xx_i2c_writeb(void *opaque, hwaddr addr, uint64_t value,
         break;
     case 0x0A:
         i2c->lsadr = value;
+        /*i2c_set_slave_address(i2c->bus, i2c->lsadr);*/
         break;
     case 0x0B:
         i2c->hsadr = value;
@@ -149,11 +290,23 @@ static void ppc4xx_i2c_writeb(void *opaque, hwaddr addr, uint64_t value,
         i2c->xfrcnt = value & 0x77;
         break;
     case 0x0F:
+        if (value & IIC_XTCNTLSS_SRST) {
+            /* Is it actually a full reset? U-Boot sets some regs before */
+            ppc4xx_i2c_reset(DEVICE(i2c));
+            break;
+        }
         i2c->xtcntlss = value;
         break;
     case 0x10:
         i2c->directcntl = value & 0x7;
         break;
+    case 0x11:
+        i2c->intr = value;
+        break;
+    default:
+        qemu_log_mask(LOG_GUEST_ERROR, "[%s]%s: Bad address at offset 0x%"
+                      HWADDR_PRIx "\n", TYPE_PPC4xx_I2C, __func__, addr);
+        break;
     }
 }
 
@@ -167,21 +320,6 @@ static const MemoryRegionOps ppc4xx_i2c_ops = {
     .endianness = DEVICE_NATIVE_ENDIAN,
 };
 
-static void ppc4xx_i2c_reset(DeviceState *s)
-{
-    PPC4xxI2CState *i2c = PPC4xx_I2C(s);
-
-    i2c->mdata = 0x00;
-    i2c->sdata = 0x00;
-    i2c->cntl = 0x00;
-    i2c->mdcntl = 0x00;
-    i2c->sts = 0x00;
-    i2c->extsts = 0x00;
-    i2c->clkdiv = 0x00;
-    i2c->xfrcnt = 0x00;
-    i2c->directcntl = 0x0F;
-}
-
 static void ppc4xx_i2c_init(Object *o)
 {
     PPC4xxI2CState *s = PPC4xx_I2C(o);