u-boot/drivers/spi/ep93xx_spi.c

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/*
* SPI Driver for EP93xx
*
* Copyright (C) 2013 Sergey Kostanabev <sergey.kostanbaev <at> fairwaves.ru>
*
* Inspired form linux kernel driver and atmel uboot driver
*
* SPDX-License-Identifier: GPL-2.0+
*/
#include <common.h>
#include <spi.h>
#include <malloc.h>
#include <asm/io.h>
#include <asm/arch/ep93xx.h>
#define BIT(x) (1<<(x))
#define SSPBASE SPI_BASE
#define SSPCR0 0x0000
#define SSPCR0_MODE_SHIFT 6
#define SSPCR0_SCR_SHIFT 8
#define SSPCR0_SPH BIT(7)
#define SSPCR0_SPO BIT(6)
#define SSPCR0_FRF_SPI 0
#define SSPCR0_DSS_8BIT 7
#define SSPCR1 0x0004
#define SSPCR1_RIE BIT(0)
#define SSPCR1_TIE BIT(1)
#define SSPCR1_RORIE BIT(2)
#define SSPCR1_LBM BIT(3)
#define SSPCR1_SSE BIT(4)
#define SSPCR1_MS BIT(5)
#define SSPCR1_SOD BIT(6)
#define SSPDR 0x0008
#define SSPSR 0x000c
#define SSPSR_TFE BIT(0)
#define SSPSR_TNF BIT(1)
#define SSPSR_RNE BIT(2)
#define SSPSR_RFF BIT(3)
#define SSPSR_BSY BIT(4)
#define SSPCPSR 0x0010
#define SSPIIR 0x0014
#define SSPIIR_RIS BIT(0)
#define SSPIIR_TIS BIT(1)
#define SSPIIR_RORIS BIT(2)
#define SSPICR SSPIIR
#define SSPCLOCK 14745600
#define SSP_MAX_RATE (SSPCLOCK / 2)
#define SSP_MIN_RATE (SSPCLOCK / (254 * 256))
/* timeout in milliseconds */
#define SPI_TIMEOUT 5
/* maximum depth of RX/TX FIFO */
#define SPI_FIFO_SIZE 8
struct ep93xx_spi_slave {
struct spi_slave slave;
unsigned sspcr0;
unsigned sspcpsr;
};
static inline struct ep93xx_spi_slave *to_ep93xx_spi(struct spi_slave *slave)
{
return container_of(slave, struct ep93xx_spi_slave, slave);
}
void spi_init()
{
}
static inline void ep93xx_spi_write_u8(u16 reg, u8 value)
{
writel(value, (unsigned int *)(SSPBASE + reg));
}
static inline u8 ep93xx_spi_read_u8(u16 reg)
{
return readl((unsigned int *)(SSPBASE + reg));
}
static inline void ep93xx_spi_write_u16(u16 reg, u16 value)
{
writel(value, (unsigned int *)(SSPBASE + reg));
}
static inline u16 ep93xx_spi_read_u16(u16 reg)
{
return (u16)readl((unsigned int *)(SSPBASE + reg));
}
static int ep93xx_spi_init_hw(unsigned int rate, unsigned int mode,
struct ep93xx_spi_slave *slave)
{
unsigned cpsr, scr;
if (rate > SSP_MAX_RATE)
rate = SSP_MAX_RATE;
if (rate < SSP_MIN_RATE)
return -1;
/* Calculate divisors so that we can get speed according the
* following formula:
* rate = spi_clock_rate / (cpsr * (1 + scr))
*
* cpsr must be even number and starts from 2, scr can be any number
* between 0 and 255.
*/
for (cpsr = 2; cpsr <= 254; cpsr += 2) {
for (scr = 0; scr <= 255; scr++) {
if ((SSPCLOCK / (cpsr * (scr + 1))) <= rate) {
/* Set CHPA and CPOL, SPI format and 8bit */
unsigned sspcr0 = (scr << SSPCR0_SCR_SHIFT) |
SSPCR0_FRF_SPI | SSPCR0_DSS_8BIT;
if (mode & SPI_CPHA)
sspcr0 |= SSPCR0_SPH;
if (mode & SPI_CPOL)
sspcr0 |= SSPCR0_SPO;
slave->sspcr0 = sspcr0;
slave->sspcpsr = cpsr;
return 0;
}
}
}
return -1;
}
void spi_set_speed(struct spi_slave *slave, unsigned int hz)
{
struct ep93xx_spi_slave *as = to_ep93xx_spi(slave);
unsigned int mode = 0;
if (as->sspcr0 & SSPCR0_SPH)
mode |= SPI_CPHA;
if (as->sspcr0 & SSPCR0_SPO)
mode |= SPI_CPOL;
ep93xx_spi_init_hw(hz, mode, as);
}
struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs,
unsigned int max_hz, unsigned int mode)
{
struct ep93xx_spi_slave *as;
if (!spi_cs_is_valid(bus, cs))
return NULL;
as = spi_alloc_slave(struct ep93xx_spi_slave, bus, cs);
if (!as)
return NULL;
if (ep93xx_spi_init_hw(max_hz, mode, as)) {
free(as);
return NULL;
}
return &as->slave;
}
void spi_free_slave(struct spi_slave *slave)
{
struct ep93xx_spi_slave *as = to_ep93xx_spi(slave);
free(as);
}
int spi_claim_bus(struct spi_slave *slave)
{
struct ep93xx_spi_slave *as = to_ep93xx_spi(slave);
/* Enable the SPI hardware */
ep93xx_spi_write_u8(SSPCR1, SSPCR1_SSE);
ep93xx_spi_write_u8(SSPCPSR, as->sspcpsr);
ep93xx_spi_write_u16(SSPCR0, as->sspcr0);
debug("Select CS:%d SSPCPSR=%02x SSPCR0=%04x\n",
slave->cs, as->sspcpsr, as->sspcr0);
return 0;
}
void spi_release_bus(struct spi_slave *slave)
{
/* Disable the SPI hardware */
ep93xx_spi_write_u8(SSPCR1, 0);
}
int spi_xfer(struct spi_slave *slave, unsigned int bitlen,
const void *dout, void *din, unsigned long flags)
{
unsigned int len_tx;
unsigned int len_rx;
unsigned int len;
u32 status;
const u8 *txp = dout;
u8 *rxp = din;
u8 value;
debug("spi_xfer: slave %u:%u dout %p din %p bitlen %u\n",
slave->bus, slave->cs, (uint *)dout, (uint *)din, bitlen);
if (bitlen == 0)
/* Finish any previously submitted transfers */
goto out;
if (bitlen % 8) {
/* Errors always terminate an ongoing transfer */
flags |= SPI_XFER_END;
goto out;
}
len = bitlen / 8;
if (flags & SPI_XFER_BEGIN) {
/* Empty RX FIFO */
while ((ep93xx_spi_read_u8(SSPSR) & SSPSR_RNE))
ep93xx_spi_read_u8(SSPDR);
spi_cs_activate(slave);
}
for (len_tx = 0, len_rx = 0; len_rx < len; ) {
status = ep93xx_spi_read_u8(SSPSR);
if ((len_tx < len) && (status & SSPSR_TNF)) {
if (txp)
value = *txp++;
else
value = 0xff;
ep93xx_spi_write_u8(SSPDR, value);
len_tx++;
}
if (status & SSPSR_RNE) {
value = ep93xx_spi_read_u8(SSPDR);
if (rxp)
*rxp++ = value;
len_rx++;
}
}
out:
if (flags & SPI_XFER_END) {
/*
* Wait until the transfer is completely done before
* we deactivate CS.
*/
do {
status = ep93xx_spi_read_u8(SSPSR);
} while (status & SSPSR_BSY);
spi_cs_deactivate(slave);
}
return 0;
}