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// SPDX-License-Identifier: GPL-2.0
//
// SPI controller driver for Qualcomm Atheros AR934x/QCA95xx SoCs
//
// Copyright (C) 2020 Chuanhong Guo <gch981213@gmail.com>
//
// Based on spi-mt7621.c:
// Copyright (C) 2011 Sergiy <piratfm@gmail.com>
// Copyright (C) 2011-2013 Gabor Juhos <juhosg@openwrt.org>
// Copyright (C) 2014-2015 Felix Fietkau <nbd@nbd.name>
#include <linux/clk.h>
#include <linux/io.h>
#include <linux/iopoll.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of_device.h>
#include <linux/spi/spi.h>
#define DRIVER_NAME "spi-ar934x"
#define AR934X_SPI_REG_FS 0x00
#define AR934X_SPI_ENABLE BIT(0)
#define AR934X_SPI_REG_IOC 0x08
#define AR934X_SPI_IOC_INITVAL 0x70000
#define AR934X_SPI_REG_CTRL 0x04
#define AR934X_SPI_CLK_MASK GENMASK(5, 0)
#define AR934X_SPI_DATAOUT 0x10
#define AR934X_SPI_REG_SHIFT_CTRL 0x14
#define AR934X_SPI_SHIFT_EN BIT(31)
#define AR934X_SPI_SHIFT_CS(n) BIT(28 + (n))
#define AR934X_SPI_SHIFT_TERM 26
#define AR934X_SPI_SHIFT_VAL(cs, term, count) \
(AR934X_SPI_SHIFT_EN | AR934X_SPI_SHIFT_CS(cs) | \
(term) << AR934X_SPI_SHIFT_TERM | (count))
#define AR934X_SPI_DATAIN 0x18
struct ar934x_spi {
struct spi_controller *ctlr;
void __iomem *base;
struct clk *clk;
unsigned int clk_freq;
};
static inline int ar934x_spi_clk_div(struct ar934x_spi *sp, unsigned int freq)
{
int div = DIV_ROUND_UP(sp->clk_freq, freq * 2) - 1;
if (div < 0)
return 0;
else if (div > AR934X_SPI_CLK_MASK)
return -EINVAL;
else
return div;
}
static int ar934x_spi_setup(struct spi_device *spi)
{
struct ar934x_spi *sp = spi_controller_get_devdata(spi->master);
if ((spi->max_speed_hz == 0) ||
(spi->max_speed_hz > (sp->clk_freq / 2))) {
spi->max_speed_hz = sp->clk_freq / 2;
} else if (spi->max_speed_hz < (sp->clk_freq / 128)) {
dev_err(&spi->dev, "spi clock is too low\n");
return -EINVAL;
}
return 0;
}
static int ar934x_spi_transfer_one_message(struct spi_controller *master,
struct spi_message *m)
{
struct ar934x_spi *sp = spi_controller_get_devdata(master);
struct spi_transfer *t = NULL;
struct spi_device *spi = m->spi;
unsigned long trx_done, trx_cur;
int stat = 0;
u8 term = 0;
int div, i;
u32 reg;
const u8 *tx_buf;
u8 *buf;
m->actual_length = 0;
list_for_each_entry(t, &m->transfers, transfer_list) {
if (t->speed_hz)
div = ar934x_spi_clk_div(sp, t->speed_hz);
else
div = ar934x_spi_clk_div(sp, spi->max_speed_hz);
if (div < 0) {
stat = -EIO;
goto msg_done;
}
reg = ioread32(sp->base + AR934X_SPI_REG_CTRL);
reg &= ~AR934X_SPI_CLK_MASK;
reg |= div;
iowrite32(reg, sp->base + AR934X_SPI_REG_CTRL);
iowrite32(0, sp->base + AR934X_SPI_DATAOUT);
for (trx_done = 0; trx_done < t->len; trx_done += 4) {
trx_cur = t->len - trx_done;
if (trx_cur > 4)
trx_cur = 4;
else if (list_is_last(&t->transfer_list, &m->transfers))
term = 1;
if (t->tx_buf) {
tx_buf = t->tx_buf + trx_done;
reg = tx_buf[0];
for (i = 1; i < trx_cur; i++)
reg = reg << 8 | tx_buf[i];
iowrite32(reg, sp->base + AR934X_SPI_DATAOUT);
}
reg = AR934X_SPI_SHIFT_VAL(spi->chip_select, term,
trx_cur * 8);
iowrite32(reg, sp->base + AR934X_SPI_REG_SHIFT_CTRL);
stat = readl_poll_timeout(
sp->base + AR934X_SPI_REG_SHIFT_CTRL, reg,
!(reg & AR934X_SPI_SHIFT_EN), 0, 5);
if (stat < 0)
goto msg_done;
if (t->rx_buf) {
reg = ioread32(sp->base + AR934X_SPI_DATAIN);
buf = t->rx_buf + trx_done;
for (i = 0; i < trx_cur; i++) {
buf[trx_cur - i - 1] = reg & 0xff;
reg >>= 8;
}
}
}
m->actual_length += t->len;
}
msg_done:
m->status = stat;
spi_finalize_current_message(master);
return 0;
}
static const struct of_device_id ar934x_spi_match[] = {
{ .compatible = "qca,ar934x-spi" },
{},
};
MODULE_DEVICE_TABLE(of, ar934x_spi_match);
static int ar934x_spi_probe(struct platform_device *pdev)
{
struct spi_controller *ctlr;
struct ar934x_spi *sp;
void __iomem *base;
struct clk *clk;
int ret;
base = devm_platform_ioremap_resource(pdev, 0);
if (IS_ERR(base))
return PTR_ERR(base);
clk = devm_clk_get(&pdev->dev, NULL);
if (IS_ERR(clk)) {
dev_err(&pdev->dev, "failed to get clock\n");
return PTR_ERR(clk);
}
ret = clk_prepare_enable(clk);
if (ret)
return ret;
ctlr = spi_alloc_master(&pdev->dev, sizeof(*sp));
if (!ctlr) {
dev_info(&pdev->dev, "failed to allocate spi controller\n");
return -ENOMEM;
}
/* disable flash mapping and expose spi controller registers */
iowrite32(AR934X_SPI_ENABLE, base + AR934X_SPI_REG_FS);
/* restore pins to default state: CSn=1 DO=CLK=0 */
iowrite32(AR934X_SPI_IOC_INITVAL, base + AR934X_SPI_REG_IOC);
ctlr->mode_bits = SPI_LSB_FIRST;
ctlr->setup = ar934x_spi_setup;
ctlr->transfer_one_message = ar934x_spi_transfer_one_message;
ctlr->bits_per_word_mask = SPI_BPW_MASK(8);
ctlr->dev.of_node = pdev->dev.of_node;
ctlr->num_chipselect = 3;
dev_set_drvdata(&pdev->dev, ctlr);
sp = spi_controller_get_devdata(ctlr);
sp->base = base;
sp->clk = clk;
sp->clk_freq = clk_get_rate(clk);
sp->ctlr = ctlr;
return devm_spi_register_controller(&pdev->dev, ctlr);
}
static int ar934x_spi_remove(struct platform_device *pdev)
{
struct spi_controller *ctlr;
struct ar934x_spi *sp;
ctlr = dev_get_drvdata(&pdev->dev);
sp = spi_controller_get_devdata(ctlr);
clk_disable_unprepare(sp->clk);
return 0;
}
static struct platform_driver ar934x_spi_driver = {
.driver = {
.name = DRIVER_NAME,
.of_match_table = ar934x_spi_match,
},
.probe = ar934x_spi_probe,
.remove = ar934x_spi_remove,
};
module_platform_driver(ar934x_spi_driver);
MODULE_DESCRIPTION("SPI controller driver for Qualcomm Atheros AR934x/QCA95xx");
MODULE_AUTHOR("Chuanhong Guo <gch981213@gmail.com>");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:" DRIVER_NAME);
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