u-boot/drivers/spi/mt7620_spi.c

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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2020 MediaTek Inc.
*
* Author: Weijie Gao <weijie.gao@mediatek.com>
*
* Generic SPI driver for MediaTek MT7620 SoC
*/
#include <clk.h>
#include <dm.h>
#include <dm/device_compat.h>
#include <spi.h>
#include <linux/bitops.h>
#include <linux/iopoll.h>
#include <linux/io.h>
#include <linux/log2.h>
#define MT7620_SPI_NUM_CS 2
#define MT7620_SPI_MASTER1_OFF 0x00
#define MT7620_SPI_MASTER2_OFF 0x40
/* SPI_STAT */
#define SPI_BUSY BIT(0)
/* SPI_CFG */
#define MSB_FIRST BIT(8)
#define SPI_CLK_POL BIT(6)
#define RX_CLK_EDGE BIT(5)
#define TX_CLK_EDGE BIT(4)
#define SPI_CLK_S 0
#define SPI_CLK_M GENMASK(2, 0)
/* SPI_CTL */
#define START_WR BIT(2)
#define START_RD BIT(1)
#define SPI_HIGH BIT(0)
#define SPI_ARB 0xf0
#define ARB_EN BIT(31)
#define POLLING_SCALE 10
#define POLLING_FRAC_USEC 100
struct mt7620_spi_master_regs {
u32 stat;
u32 reserved0[3];
u32 cfg;
u32 ctl;
u32 reserved1[2];
u32 data;
};
struct mt7620_spi {
void __iomem *regs;
struct mt7620_spi_master_regs *m[MT7620_SPI_NUM_CS];
unsigned int sys_freq;
u32 wait_us;
uint mode;
uint speed;
};
static void mt7620_spi_master_setup(struct mt7620_spi *ms, int cs)
{
u32 rate, prescale, freq, tmo, cfg;
/* Calculate the clock divsior */
rate = DIV_ROUND_UP(ms->sys_freq, ms->speed);
rate = roundup_pow_of_two(rate);
prescale = ilog2(rate / 2);
if (prescale > 6)
prescale = 6;
/* Calculate the real clock, and usecs for one byte transaction */
freq = ms->sys_freq >> (prescale + 1);
tmo = DIV_ROUND_UP(8 * 1000000, freq);
/* 10 times tolerance plus 100us */
ms->wait_us = POLLING_SCALE * tmo + POLLING_FRAC_USEC;
/* set SPI_CFG */
cfg = prescale << SPI_CLK_S;
switch (ms->mode & (SPI_CPOL | SPI_CPHA)) {
case SPI_MODE_0:
cfg |= TX_CLK_EDGE;
break;
case SPI_MODE_1:
cfg |= RX_CLK_EDGE;
break;
case SPI_MODE_2:
cfg |= SPI_CLK_POL | RX_CLK_EDGE;
break;
case SPI_MODE_3:
cfg |= SPI_CLK_POL | TX_CLK_EDGE;
break;
}
if (!(ms->mode & SPI_LSB_FIRST))
cfg |= MSB_FIRST;
writel(cfg, &ms->m[cs]->cfg);
writel(SPI_HIGH, &ms->m[cs]->ctl);
}
static void mt7620_spi_set_cs(struct mt7620_spi *ms, int cs, bool enable)
{
if (enable)
mt7620_spi_master_setup(ms, cs);
if (ms->mode & SPI_CS_HIGH)
enable = !enable;
if (enable)
clrbits_32(&ms->m[cs]->ctl, SPI_HIGH);
else
setbits_32(&ms->m[cs]->ctl, SPI_HIGH);
}
static int mt7620_spi_set_mode(struct udevice *bus, uint mode)
{
struct mt7620_spi *ms = dev_get_priv(bus);
ms->mode = mode;
/* Mode 0 is buggy. Force to use mode 3 */
if ((mode & SPI_MODE_3) == SPI_MODE_0)
ms->mode |= SPI_MODE_3;
return 0;
}
static int mt7620_spi_set_speed(struct udevice *bus, uint speed)
{
struct mt7620_spi *ms = dev_get_priv(bus);
ms->speed = speed;
return 0;
}
static inline int mt7620_spi_busy_poll(struct mt7620_spi *ms, int cs)
{
u32 val;
return readl_poll_timeout(&ms->m[cs]->stat, val, !(val & SPI_BUSY),
ms->wait_us);
}
static int mt7620_spi_read(struct mt7620_spi *ms, int cs, u8 *buf, size_t len)
{
int ret;
while (len) {
setbits_32(&ms->m[cs]->ctl, START_RD);
ret = mt7620_spi_busy_poll(ms, cs);
if (ret)
return ret;
*buf++ = (u8)readl(&ms->m[cs]->data);
len--;
}
return 0;
}
static int mt7620_spi_write(struct mt7620_spi *ms, int cs, const u8 *buf,
size_t len)
{
int ret;
while (len) {
writel(*buf++, &ms->m[cs]->data);
setbits_32(&ms->m[cs]->ctl, START_WR);
ret = mt7620_spi_busy_poll(ms, cs);
if (ret)
return ret;
len--;
}
return 0;
}
static int mt7620_spi_xfer(struct udevice *dev, unsigned int bitlen,
const void *dout, void *din, unsigned long flags)
{
struct udevice *bus = dev->parent;
struct mt7620_spi *ms = dev_get_priv(bus);
int total_size = bitlen >> 3;
int cs, ret = 0;
/*
* This driver only supports half-duplex, so complain and bail out
* upon full-duplex messages
*/
if (dout && din) {
dev_err(dev, "mt7620_spi: Only half-duplex is supported\n");
return -EIO;
}
cs = spi_chip_select(dev);
if (cs < 0 || cs >= MT7620_SPI_NUM_CS) {
dev_err(dev, "mt7620_spi: Invalid chip select %d\n", cs);
return -EINVAL;
}
if (flags & SPI_XFER_BEGIN)
mt7620_spi_set_cs(ms, cs, true);
if (din)
ret = mt7620_spi_read(ms, cs, din, total_size);
else if (dout)
ret = mt7620_spi_write(ms, cs, dout, total_size);
if (ret)
dev_err(dev, "mt7620_spi: %s transaction timeout\n",
din ? "read" : "write");
if (flags & SPI_XFER_END)
mt7620_spi_set_cs(ms, cs, false);
return ret;
}
static int mt7620_spi_probe(struct udevice *dev)
{
struct mt7620_spi *ms = dev_get_priv(dev);
struct clk clk;
int ret;
ms->regs = dev_remap_addr(dev);
if (!ms->regs)
return -EINVAL;
ms->m[0] = ms->regs + MT7620_SPI_MASTER1_OFF;
ms->m[1] = ms->regs + MT7620_SPI_MASTER2_OFF;
ret = clk_get_by_index(dev, 0, &clk);
if (ret < 0) {
dev_err(dev, "mt7620_spi: Please provide a clock!\n");
return ret;
}
clk_enable(&clk);
ms->sys_freq = clk_get_rate(&clk);
if (!ms->sys_freq) {
dev_err(dev, "mt7620_spi: Please provide a valid bus clock!\n");
return -EINVAL;
}
writel(ARB_EN, ms->regs + SPI_ARB);
return 0;
}
static const struct dm_spi_ops mt7620_spi_ops = {
.set_mode = mt7620_spi_set_mode,
.set_speed = mt7620_spi_set_speed,
.xfer = mt7620_spi_xfer,
};
static const struct udevice_id mt7620_spi_ids[] = {
{ .compatible = "mediatek,mt7620-spi" },
{ }
};
U_BOOT_DRIVER(mt7620_spi) = {
.name = "mt7620_spi",
.id = UCLASS_SPI,
.of_match = mt7620_spi_ids,
.ops = &mt7620_spi_ops,
.priv_auto = sizeof(struct mt7620_spi),
.probe = mt7620_spi_probe,
};