[PATCH 1/5] hw/i2c: pmbus add support for block receive

[Titus Rwantare]

Reviewed-by: Hao Wu <wuhaotsh@google.com>
Signed-off-by: Titus Rwantare <titusr@google.com>
---
 hw/i2c/pmbus_device.c         | 30 +++++++++++++++++++++++++++++-
 include/hw/i2c/pmbus_device.h |  7 +++++++
 2 files changed, 36 insertions(+), 1 deletion(-)

diff --git a/hw/i2c/pmbus_device.c b/hw/i2c/pmbus_device.c
index c3d6046784..02647769cd 100644
--- a/hw/i2c/pmbus_device.c
+++ b/hw/i2c/pmbus_device.c
@@ -95,7 +95,6 @@ void pmbus_send64(PMBusDevice *pmdev, uint64_t data)
 void pmbus_send_string(PMBusDevice *pmdev, const char *data)
 {
     size_t len = strlen(data);
-    g_assert(len > 0);
     g_assert(len + pmdev->out_buf_len < SMBUS_DATA_MAX_LEN);
     pmdev->out_buf[len + pmdev->out_buf_len] = len;
 
@@ -105,6 +104,35 @@ void pmbus_send_string(PMBusDevice *pmdev, const char 
*data)
     pmdev->out_buf_len += len + 1;
 }
 
+uint8_t pmbus_receive_block(PMBusDevice *pmdev, uint8_t *dest, size_t len)
+{
+    /* dest may contain data from previous writes */
+    memset(dest, 0, len);
+
+    /* Exclude command code from return value */
+    pmdev->in_buf++;
+    pmdev->in_buf_len--;
+
+    /* The byte after the command code denotes the length */
+    uint8_t sent_len = pmdev->in_buf[0];
+
+    if (sent_len != pmdev->in_buf_len - 1) {
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "%s: length mismatch. Expected %d bytes, got %d bytes\n",
+                      __func__, sent_len, pmdev->in_buf_len - 1);
+    }
+
+    /* exclude length byte */
+    pmdev->in_buf++;
+    pmdev->in_buf_len--;
+
+    if (pmdev->in_buf_len < len) {
+        len = pmdev->in_buf_len;
+    }
+    memcpy(dest, pmdev->in_buf, len);
+    return len;
+}
+
 
 static uint64_t pmbus_receive_uint(PMBusDevice *pmdev)
 {
diff --git a/include/hw/i2c/pmbus_device.h b/include/hw/i2c/pmbus_device.h
index 93f5d57c9d..7dc00cc4d9 100644
--- a/include/hw/i2c/pmbus_device.h
+++ b/include/hw/i2c/pmbus_device.h
@@ -501,6 +501,13 @@ void pmbus_send64(PMBusDevice *state, uint64_t data);
  */
 void pmbus_send_string(PMBusDevice *state, const char *data);
 
+/**
+ * @brief Receive data sent with Block Write.
+ * @param dest - memory with enough capacity to receive the write
+ * @param len - the capacity of dest
+ */
+uint8_t pmbus_receive_block(PMBusDevice *pmdev, uint8_t *dest, size_t len);
+
 /**
  * @brief Receive data over PMBus
  * These methods help track how much data is being received over PMBus
-- 
2.40.0.rc1.284.g88254d51c5-goog