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/*
* SPI-Engine SPI controller driver
* Copyright 2015 Analog Devices Inc.
* Author: Lars-Peter Clausen <lars@metafoo.de>
*
* Licensed under the GPL-2.
*/
#include <linux/clk.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/of.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/spi/spi.h>
#define SPI_ENGINE_VERSION_MAJOR(x) ((x >> 16) & 0xff)
#define SPI_ENGINE_VERSION_MINOR(x) ((x >> 8) & 0xff)
#define SPI_ENGINE_VERSION_PATCH(x) (x & 0xff)
#define SPI_ENGINE_REG_VERSION 0x00
#define SPI_ENGINE_REG_RESET 0x40
#define SPI_ENGINE_REG_INT_ENABLE 0x80
#define SPI_ENGINE_REG_INT_PENDING 0x84
#define SPI_ENGINE_REG_INT_SOURCE 0x88
#define SPI_ENGINE_REG_SYNC_ID 0xc0
#define SPI_ENGINE_REG_CMD_FIFO_ROOM 0xd0
#define SPI_ENGINE_REG_SDO_FIFO_ROOM 0xd4
#define SPI_ENGINE_REG_SDI_FIFO_LEVEL 0xd8
#define SPI_ENGINE_REG_CMD_FIFO 0xe0
#define SPI_ENGINE_REG_SDO_DATA_FIFO 0xe4
#define SPI_ENGINE_REG_SDI_DATA_FIFO 0xe8
#define SPI_ENGINE_REG_SDI_DATA_FIFO_PEEK 0xec
#define SPI_ENGINE_INT_CMD_ALMOST_EMPTY BIT(0)
#define SPI_ENGINE_INT_SDO_ALMOST_EMPTY BIT(1)
#define SPI_ENGINE_INT_SDI_ALMOST_FULL BIT(2)
#define SPI_ENGINE_INT_SYNC BIT(3)
#define SPI_ENGINE_CONFIG_CPHA BIT(0)
#define SPI_ENGINE_CONFIG_CPOL BIT(1)
#define SPI_ENGINE_CONFIG_3WIRE BIT(2)
#define SPI_ENGINE_INST_TRANSFER 0x0
#define SPI_ENGINE_INST_ASSERT 0x1
#define SPI_ENGINE_INST_WRITE 0x2
#define SPI_ENGINE_INST_MISC 0x3
#define SPI_ENGINE_CMD_REG_CLK_DIV 0x0
#define SPI_ENGINE_CMD_REG_CONFIG 0x1
#define SPI_ENGINE_MISC_SYNC 0x0
#define SPI_ENGINE_MISC_SLEEP 0x1
#define SPI_ENGINE_TRANSFER_WRITE 0x1
#define SPI_ENGINE_TRANSFER_READ 0x2
#define SPI_ENGINE_CMD(inst, arg1, arg2) \
(((inst) << 12) | ((arg1) << 8) | (arg2))
#define SPI_ENGINE_CMD_TRANSFER(flags, n) \
SPI_ENGINE_CMD(SPI_ENGINE_INST_TRANSFER, (flags), (n))
#define SPI_ENGINE_CMD_ASSERT(delay, cs) \
SPI_ENGINE_CMD(SPI_ENGINE_INST_ASSERT, (delay), (cs))
#define SPI_ENGINE_CMD_WRITE(reg, val) \
SPI_ENGINE_CMD(SPI_ENGINE_INST_WRITE, (reg), (val))
#define SPI_ENGINE_CMD_SLEEP(delay) \
SPI_ENGINE_CMD(SPI_ENGINE_INST_MISC, SPI_ENGINE_MISC_SLEEP, (delay))
#define SPI_ENGINE_CMD_SYNC(id) \
SPI_ENGINE_CMD(SPI_ENGINE_INST_MISC, SPI_ENGINE_MISC_SYNC, (id))
struct spi_engine_program {
unsigned int length;
uint16_t instructions[];
};
struct spi_engine {
struct clk *clk;
struct clk *ref_clk;
spinlock_t lock;
void __iomem *base;
struct spi_message *msg;
struct spi_engine_program *p;
unsigned cmd_length;
const uint16_t *cmd_buf;
struct spi_transfer *tx_xfer;
unsigned int tx_length;
const uint8_t *tx_buf;
struct spi_transfer *rx_xfer;
unsigned int rx_length;
uint8_t *rx_buf;
unsigned int sync_id;
unsigned int completed_id;
unsigned int int_enable;
};
static void spi_engine_program_add_cmd(struct spi_engine_program *p,
bool dry, uint16_t cmd)
{
if (!dry)
p->instructions[p->length] = cmd;
p->length++;
}
static unsigned int spi_engine_get_config(struct spi_device *spi)
{
unsigned int config = 0;
if (spi->mode & SPI_CPOL)
config |= SPI_ENGINE_CONFIG_CPOL;
if (spi->mode & SPI_CPHA)
config |= SPI_ENGINE_CONFIG_CPHA;
if (spi->mode & SPI_3WIRE)
config |= SPI_ENGINE_CONFIG_3WIRE;
return config;
}
static unsigned int spi_engine_get_clk_div(struct spi_engine *spi_engine,
struct spi_device *spi, struct spi_transfer *xfer)
{
unsigned int clk_div;
clk_div = DIV_ROUND_UP(clk_get_rate(spi_engine->ref_clk),
xfer->speed_hz * 2);
if (clk_div > 255)
clk_div = 255;
else if (clk_div > 0)
clk_div -= 1;
return clk_div;
}
static void spi_engine_gen_xfer(struct spi_engine_program *p, bool dry,
struct spi_transfer *xfer)
{
unsigned int len = xfer->len;
while (len) {
unsigned int n = min(len, 256U);
unsigned int flags = 0;
if (xfer->tx_buf)
flags |= SPI_ENGINE_TRANSFER_WRITE;
if (xfer->rx_buf)
flags |= SPI_ENGINE_TRANSFER_READ;
spi_engine_program_add_cmd(p, dry,
SPI_ENGINE_CMD_TRANSFER(flags, n - 1));
len -= n;
}
}
static void spi_engine_gen_sleep(struct spi_engine_program *p, bool dry,
struct spi_engine *spi_engine, unsigned int clk_div, unsigned int delay)
{
unsigned int spi_clk = clk_get_rate(spi_engine->ref_clk);
unsigned int t;
if (delay == 0)
return;
t = DIV_ROUND_UP(delay * spi_clk, (clk_div + 1) * 2);
while (t) {
unsigned int n = min(t, 256U);
spi_engine_program_add_cmd(p, dry, SPI_ENGINE_CMD_SLEEP(n - 1));
t -= n;
}
}
static void spi_engine_gen_cs(struct spi_engine_program *p, bool dry,
struct spi_device *spi, bool assert)
{
unsigned int mask = 0xff;
if (assert)
mask ^= BIT(spi->chip_select);
spi_engine_program_add_cmd(p, dry, SPI_ENGINE_CMD_ASSERT(1, mask));
}
static int spi_engine_compile_message(struct spi_engine *spi_engine,
struct spi_message *msg, bool dry, struct spi_engine_program *p)
{
struct spi_device *spi = msg->spi;
struct spi_transfer *xfer;
int clk_div, new_clk_div;
bool cs_change = true;
clk_div = -1;
spi_engine_program_add_cmd(p, dry,
SPI_ENGINE_CMD_WRITE(SPI_ENGINE_CMD_REG_CONFIG,
spi_engine_get_config(spi)));
list_for_each_entry(xfer, &msg->transfers, transfer_list) {
new_clk_div = spi_engine_get_clk_div(spi_engine, spi, xfer);
if (new_clk_div != clk_div) {
clk_div = new_clk_div;
spi_engine_program_add_cmd(p, dry,
SPI_ENGINE_CMD_WRITE(SPI_ENGINE_CMD_REG_CLK_DIV,
clk_div));
}
if (cs_change)
spi_engine_gen_cs(p, dry, spi, true);
spi_engine_gen_xfer(p, dry, xfer);
spi_engine_gen_sleep(p, dry, spi_engine, clk_div,
xfer->delay_usecs);
cs_change = xfer->cs_change;
if (list_is_last(&xfer->transfer_list, &msg->transfers))
cs_change = !cs_change;
if (cs_change)
spi_engine_gen_cs(p, dry, spi, false);
}
return 0;
}
static void spi_engine_xfer_next(struct spi_engine *spi_engine,
struct spi_transfer **_xfer)
{
struct spi_message *msg = spi_engine->msg;
struct spi_transfer *xfer = *_xfer;
if (!xfer) {
xfer = list_first_entry(&msg->transfers,
struct spi_transfer, transfer_list);
} else if (list_is_last(&xfer->transfer_list, &msg->transfers)) {
xfer = NULL;
} else {
xfer = list_next_entry(xfer, transfer_list);
}
*_xfer = xfer;
}
static void spi_engine_tx_next(struct spi_engine *spi_engine)
{
struct spi_transfer *xfer = spi_engine->tx_xfer;
do {
spi_engine_xfer_next(spi_engine, &xfer);
} while (xfer && !xfer->tx_buf);
spi_engine->tx_xfer = xfer;
if (xfer) {
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