From 5fe9dd5a5036e528d6180ef629d38d454e4744a3 Mon Sep 17 00:00:00 2001
From: Arksine <arksine.code@gmail.com>
Date: Thu, 9 Jan 2020 19:24:51 -0500
Subject: avr: implement i2c_read

Signed-off-by:  Eric Callahan <arksine.code@gmail.com>
---
 src/avr/i2c.c | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

(limited to 'src/avr')

diff --git a/src/avr/i2c.c b/src/avr/i2c.c
index 4632497e..370582cc 100644
--- a/src/avr/i2c.c
+++ b/src/avr/i2c.c
@@ -84,6 +84,14 @@ i2c_send_byte(uint8_t b, uint32_t timeout)
     i2c_wait(timeout);
 }
 
+static void
+i2c_receive_byte(uint8_t *read, uint32_t timeout, uint8_t send_ack)
+{
+    TWCR = (1<<TWEN) | (1<<TWINT) | ((send_ack?1:0)<<TWEA);
+    i2c_wait(timeout);
+    *read = TWDR;
+}
+
 static void
 i2c_stop(uint32_t timeout)
 {
@@ -106,5 +114,14 @@ void
 i2c_read(struct i2c_config config, uint8_t reg_len, uint8_t *reg
          , uint8_t read_len, uint8_t *read)
 {
-    shutdown("i2c_read not supported on avr");
+    uint32_t timeout = timer_read_time() + timer_from_us(5000);
+    i2c_start(timeout);
+    i2c_send_byte(config.addr, timeout);
+    while (reg_len--)
+        i2c_send_byte(*reg++, timeout);
+    i2c_start(timeout);
+    i2c_send_byte(config.addr | 0x1, timeout);
+    while (read_len--)
+        i2c_receive_byte(read++, timeout, read_len);
+    i2c_stop(timeout);
 }
-- 
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