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Changed formatting and added new UART divsor calculation from OpenSBI.

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This commit is contained in:
Jacob Pease 2024-07-25 13:04:27 -05:00
parent 336a413f31
commit a36e846b02
1 changed files with 45 additions and 46 deletions
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91
fpga/zsbl/uart.c
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@ -3,94 +3,93 @@
void write_reg_u8(uintptr_t addr, uint8_t value)
{
volatile uint8_t *loc_addr = (volatile uint8_t *)addr;
*loc_addr = value;
volatile uint8_t *loc_addr = (volatile uint8_t *)addr;
*loc_addr = value;
}
uint8_t read_reg_u8(uintptr_t addr)
{
return *(volatile uint8_t *)addr;
return *(volatile uint8_t *)addr;
}
int is_transmit_empty()
{
return read_reg_u8(UART_LSR) & 0x20;
return read_reg_u8(UART_LSR) & 0x20;
}
int is_receive_empty()
{
return !(read_reg_u8(UART_LSR) & 0x1);
return !(read_reg_u8(UART_LSR) & 0x1);
}
void write_serial(char a)
{
while (is_transmit_empty() == 0) {};
while (is_transmit_empty() == 0) {};
write_reg_u8(UART_THR, a);
write_reg_u8(UART_THR, a);
}
void init_uart(uint32_t freq, uint32_t baud)
{
uint32_t divisor = freq / (baud << 4);
// Alternative divisor calculation. From OpenSBI code.
// Reduces error for every possible frequency.
uint32_t divisor = (freq + 8 * baud) /(baud << 4);
write_reg_u8(UART_IER, 0x00); // Disable all interrupts
write_reg_u8(UART_LCR, 0x80); // Enable DLAB (set baud rate divisor)
write_reg_u8(UART_DLL, divisor & 0xFF); // divisor (lo byte)
write_reg_u8(UART_DLM, (divisor >> 8) & 0xFF); // divisor (hi byte)
write_reg_u8(UART_LCR, 0x03); // 8 bits, no parity, one stop bit
write_reg_u8(UART_FCR, 0xC7); // Enable FIFO, clear them, with 14-byte threshold
write_reg_u8(UART_IER, 0x00); // Disable all interrupts
write_reg_u8(UART_LCR, 0x80); // Enable DLAB (set baud rate divisor)
write_reg_u8(UART_DLL, divisor & 0xFF); // divisor (lo byte)
write_reg_u8(UART_DLM, (divisor >> 8) & 0xFF); // divisor (hi byte)
write_reg_u8(UART_LCR, 0x03); // 8 bits, no parity, one stop bit
write_reg_u8(UART_FCR, 0xC7); // Enable FIFO, clear them, with 14-byte threshold
}
void print_uart(const char *str)
{
const char *cur = &str[0];
while (*cur != '\0')
{
write_serial((uint8_t)*cur);
++cur;
}
const char *cur = &str[0];
while (*cur != '\0') {
write_serial((uint8_t)*cur);
++cur;
}
}
uint8_t bin_to_hex_table[16] = {
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'};
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'};
void bin_to_hex(uint8_t inp, uint8_t res[2])
{
res[1] = bin_to_hex_table[inp & 0xf];
res[0] = bin_to_hex_table[(inp >> 4) & 0xf];
return;
res[1] = bin_to_hex_table[inp & 0xf];
res[0] = bin_to_hex_table[(inp >> 4) & 0xf];
return;
}
void print_uart_int(uint32_t addr)
{
int i;
for (i = 3; i > -1; i--)
{
uint8_t cur = (addr >> (i * 8)) & 0xff;
uint8_t hex[2];
bin_to_hex(cur, hex);
write_serial(hex[0]);
write_serial(hex[1]);
}
int i;
for (i = 3; i > -1; i--) {
uint8_t cur = (addr >> (i * 8)) & 0xff;
uint8_t hex[2];
bin_to_hex(cur, hex);
write_serial(hex[0]);
write_serial(hex[1]);
}
}
void print_uart_addr(uint64_t addr)
{
int i;
for (i = 7; i > -1; i--)
{
uint8_t cur = (addr >> (i * 8)) & 0xff;
uint8_t hex[2];
bin_to_hex(cur, hex);
write_serial(hex[0]);
write_serial(hex[1]);
}
int i;
for (i = 7; i > -1; i--) {
uint8_t cur = (addr >> (i * 8)) & 0xff;
uint8_t hex[2];
bin_to_hex(cur, hex);
write_serial(hex[0]);
write_serial(hex[1]);
}
}
void print_uart_byte(uint8_t byte)
{
uint8_t hex[2];
bin_to_hex(byte, hex);
write_serial(hex[0]);
write_serial(hex[1]);
uint8_t hex[2];
bin_to_hex(byte, hex);
write_serial(hex[0]);
write_serial(hex[1]);
}