From a1b7a1fb1f5a5ad5b6f34b576dd0a1a2cce2f210 Mon Sep 17 00:00:00 2001
From: Uros Majstorovic <majstor@majstor.org>
Date: Wed, 24 Feb 2021 03:17:51 +0100
Subject: i2c driver initial import

---
 fw/fe310/eos/i2c.c | 116 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 fw/fe310/eos/i2c.h |   9 +++++
 2 files changed, 125 insertions(+)
 create mode 100644 fw/fe310/eos/i2c.c
 create mode 100644 fw/fe310/eos/i2c.h

(limited to 'fw/fe310/eos')

diff --git a/fw/fe310/eos/i2c.c b/fw/fe310/eos/i2c.c
new file mode 100644
index 0000000..72e53ae
--- /dev/null
+++ b/fw/fe310/eos/i2c.c
@@ -0,0 +1,116 @@
+#include <stdlib.h>
+#include <stdint.h>
+
+#include "encoding.h"
+#include "platform.h"
+#include "prci_driver.h"
+
+#include "eos.h"
+#include "i2c.h"
+
+void eos_i2c_start(uint32_t baud_rate) {
+    eos_i2c_set_baud_rate(baud_rate);
+
+    GPIO_REG(GPIO_PULLUP_EN)    &= ~(1 << IOF_I2C0_SCL);
+    GPIO_REG(GPIO_OUTPUT_XOR)   &= ~(1 << IOF_I2C0_SCL);
+
+    GPIO_REG(GPIO_PULLUP_EN)    &= ~(1 << IOF_I2C0_SDA);
+    GPIO_REG(GPIO_OUTPUT_XOR)   &= ~(1 << IOF_I2C0_SDA);
+
+    GPIO_REG(GPIO_IOF_SEL)      &= ~IOF0_I2C0_MASK;
+    GPIO_REG(GPIO_IOF_EN)       |=  IOF0_I2C0_MASK;
+}
+
+void eos_i2c_stop(void) {
+    GPIO_REG(GPIO_PULLUP_EN)    |=  (1 << IOF_I2C0_SCL);
+    GPIO_REG(GPIO_PULLUP_EN)    |=  (1 << IOF_I2C0_SDA);
+    GPIO_REG(GPIO_IOF_EN)       &=  ~IOF0_I2C0_MASK;
+}
+
+void eos_i2c_set_baud_rate(uint32_t baud_rate) {
+    unsigned long clock_rate = PRCI_get_cpu_freq();
+    uint16_t prescaler = (clock_rate / (baud_rate * 5)) - 1;
+
+    I2C0_REGB(I2C_CONTROL) &= ~I2C_CONTROL_EN;
+    I2C0_REGB(I2C_PRESCALE_LOW) = prescaler & 0xFF;
+    I2C0_REGB(I2C_PRESCALE_HIGH) = (prescaler >> 8) & 0xFF;
+    I2C0_REGB(I2C_CONTROL) |= I2C_CONTROL_EN;
+}
+
+
+static int i2c_addr(uint8_t addr, uint8_t rw_flag) {
+    I2C0_REGB(I2C_TRANSMIT) = ((addr & 0x7F) << 1) | (rw_flag & 0x1);
+    I2C0_REGB(I2C_COMMAND) = I2C_CMD_START | I2C_CMD_WRITE;
+    while (I2C0_REGB(I2C_STATUS) & I2C_STATUS_TIP);
+
+    if (I2C0_REGB(I2C_STATUS) & I2C_STATUS_RXACK) return EOS_ERR;
+    return EOS_OK;
+}
+
+static int i2c_reg(uint8_t reg) {
+    I2C0_REGB(I2C_TRANSMIT) = reg;
+    I2C0_REGB(I2C_COMMAND) = I2C_CMD_WRITE;
+    while (I2C0_REGB(I2C_STATUS) & I2C_STATUS_TIP);
+
+    if (I2C0_REGB(I2C_STATUS) & I2C_STATUS_RXACK) return EOS_ERR;
+    return EOS_OK;
+}
+
+int eos_i2c_read(uint8_t addr, uint8_t reg, uint8_t *buffer, uint16_t len) {
+    uint8_t cmd;
+    int rv;
+    int i;
+
+    rv = i2c_addr(addr, I2C_WRITE);
+    if (rv) return rv;
+
+    rv = i2c_reg(reg);
+    if (rv) return rv;
+
+    rv = i2c_addr(addr, I2C_READ);
+    if (rv) return rv;
+
+    cmd = I2C_CMD_READ;
+
+    for (i=0; i<len; i++) {
+        /* Set NACK to end read, and generate STOP condition */
+        if (i == (len - 1)) cmd |= I2C_CMD_ACK | I2C_CMD_STOP;
+        I2C0_REGB(I2C_COMMAND) = cmd;
+        while (I2C0_REGB(I2C_STATUS) & I2C_STATUS_TIP);
+        buffer[i] = I2C0_REGB(I2C_RECEIVE);
+    }
+
+    return EOS_OK;
+}
+
+int eos_i2c_write(uint8_t addr, uint8_t reg, uint8_t *buffer, uint16_t len) {
+    uint8_t cmd;
+    int rv;
+    int i;
+
+    rv = i2c_addr(addr, I2C_WRITE);
+    if (rv) return rv;
+
+    rv = i2c_reg(reg);
+    if (rv) return rv;
+
+    cmd = I2C_CMD_WRITE;
+
+    for (i=0; i<len; i++) {
+        if (i == (len - 1)) cmd |= I2C_CMD_STOP;
+        I2C0_REGB(I2C_TRANSMIT) = buffer[i];
+        I2C0_REGB(I2C_COMMAND) = cmd;
+        while (I2C0_REGB(I2C_STATUS) & I2C_STATUS_TIP);
+        if (I2C0_REGB(I2C_STATUS) & I2C_STATUS_RXACK) return EOS_ERR;
+    }
+
+    return EOS_OK;
+}
+
+int eos_i2c_read8(uint8_t addr, uint8_t reg, uint8_t *data) {
+    return eos_i2c_read(addr, reg, data, 1);
+}
+
+int eos_i2c_write8(uint8_t addr, uint8_t reg, uint8_t data) {
+    return eos_i2c_write(addr, reg, &data, 1);
+}
diff --git a/fw/fe310/eos/i2c.h b/fw/fe310/eos/i2c.h
new file mode 100644
index 0000000..9692ea0
--- /dev/null
+++ b/fw/fe310/eos/i2c.h
@@ -0,0 +1,9 @@
+#include <stdint.h>
+
+void eos_i2c_start(uint32_t baud_rate);
+void eos_i2c_stop(void);
+void eos_i2c_set_baud_rate(uint32_t baud_rate);
+int eos_i2c_read(uint8_t addr, uint8_t reg, uint8_t *buffer, uint16_t len);
+int eos_i2c_write(uint8_t addr, uint8_t reg, uint8_t *buffer, uint16_t len);
+int eos_i2c_read8(uint8_t addr, uint8_t reg, uint8_t *data);
+int eos_i2c_write8(uint8_t addr, uint8_t reg, uint8_t data);
-- 
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