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// SPDX-License-Identifier: GPL-2.0-only
/*
* SPI controller driver for the Mikrotik RB4xx boards
*
* Copyright (C) 2010 Gabor Juhos <juhosg@openwrt.org>
* Copyright (C) 2015 Bert Vermeulen <bert@biot.com>
*
* This file was based on the patches for Linux 2.6.27.39 published by
* MikroTik for their RouterBoard 4xx series devices.
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/clk.h>
#include <linux/spi/spi.h>
#include <asm/mach-ath79/ar71xx_regs.h>
struct rb4xx_spi {
void __iomem *base;
struct clk *clk;
};
static inline u32 rb4xx_read(struct rb4xx_spi *rbspi, u32 reg)
{
return __raw_readl(rbspi->base + reg);
}
static inline void rb4xx_write(struct rb4xx_spi *rbspi, u32 reg, u32 value)
{
__raw_writel(value, rbspi->base + reg);
}
static inline void do_spi_clk(struct rb4xx_spi *rbspi, u32 spi_ioc, int value)
{
u32 regval;
regval = spi_ioc;
if (value & BIT(0))
regval |= AR71XX_SPI_IOC_DO;
rb4xx_write(rbspi, AR71XX_SPI_REG_IOC, regval);
rb4xx_write(rbspi, AR71XX_SPI_REG_IOC, regval | AR71XX_SPI_IOC_CLK);
}
static void do_spi_byte(struct rb4xx_spi *rbspi, u32 spi_ioc, u8 byte)
{
int i;
for (i = 7; i >= 0; i--)
do_spi_clk(rbspi, spi_ioc, byte >> i);
}
/* The CS2 pin is used to clock in a second bit per clock cycle. */
static inline void do_spi_clk_two(struct rb4xx_spi *rbspi, u32 spi_ioc,
u8 value)
{
u32 regval;
regval = spi_ioc;
if (value & BIT(1))
regval |= AR71XX_SPI_IOC_DO;
if (value & BIT(0))
regval |= AR71XX_SPI_IOC_CS2;
rb4xx_write(rbspi, AR71XX_SPI_REG_IOC, regval);
rb4xx_write(rbspi, AR71XX_SPI_REG_IOC, regval | AR71XX_SPI_IOC_CLK);
}
/* Two bits at a time, msb first */
static void do_spi_byte_two(struct rb4xx_spi *rbspi, u32 spi_ioc, u8 byte)
{
do_spi_clk_two(rbspi, spi_ioc, byte >> 6);
do_spi_clk_two(rbspi, spi_ioc, byte >> 4);
do_spi_clk_two(rbspi, spi_ioc, byte >> 2);
do_spi_clk_two(rbspi, spi_ioc, byte >> 0);
}
static void rb4xx_set_cs(struct spi_device *spi, bool enable)
{
struct rb4xx_spi *rbspi = spi_master_get_devdata(spi->master);
/*
* Setting CS is done along with bitbanging the actual values,
* since it's all on the same hardware register. However the
* CPLD needs CS deselected after every command.
*/
if (enable)
rb4xx_write(rbspi, AR71XX_SPI_REG_IOC,
AR71XX_SPI_IOC_CS0 | AR71XX_SPI_IOC_CS1);
}
static int rb4xx_transfer_one(struct spi_master *master,
struct spi_device *spi, struct spi_transfer *t)
{
struct rb4xx_spi *rbspi = spi_master_get_devdata(master);
int i;
u32 spi_ioc;
u8 *rx_buf;
const u8 *tx_buf;
/*
* Prime the SPI register with the SPI device selected. The m25p80 boot
* flash and CPLD share the CS0 pin. This works because the CPLD's
* command set was designed to almost not clash with that of the
* boot flash.
*/
if (spi->chip_select == 2)
/* MMC */
spi_ioc = AR71XX_SPI_IOC_CS0;
else
/* Boot flash and CPLD */
spi_ioc = AR71XX_SPI_IOC_CS1;
tx_buf = t->tx_buf;
rx_buf = t->rx_buf;
for (i = 0; i < t->len; ++i) {
if (t->tx_nbits == SPI_NBITS_DUAL)
/* CPLD can use two-wire transfers */
do_spi_byte_two(rbspi, spi_ioc, tx_buf[i]);
else
do_spi_byte(rbspi, spi_ioc, tx_buf[i]);
if (!rx_buf)
continue;
rx_buf[i] = rb4xx_read(rbspi, AR71XX_SPI_REG_RDS);
}
spi_finalize_current_transfer(master);
return 0;
}
static int rb4xx_spi_probe(struct platform_device *pdev)
{
struct spi_master *master;
struct clk *ahb_clk;
struct rb4xx_spi *rbspi;
int err;
void __iomem *spi_base;
spi_base = devm_platform_ioremap_resource(pdev, 0);
if (IS_ERR(spi_base))
return PTR_ERR(spi_base);
master = spi_alloc_master(&pdev->dev, sizeof(*rbspi));
if (!master)
return -ENOMEM;
ahb_clk = devm_clk_get(&pdev->dev, "ahb");
if (IS_ERR(ahb_clk))
return PTR_ERR(ahb_clk);
master->bus_num = 0;
master->num_chipselect = 3;
master->mode_bits = SPI_TX_DUAL;
master->bits_per_word_mask = SPI_BPW_MASK(8);
master->flags = SPI_MASTER_MUST_TX;
master->transfer_one = rb4xx_transfer_one;
master->set_cs = rb4xx_set_cs;
err = devm_spi_register_master(&pdev->dev, master);
if (err) {
dev_err(&pdev->dev, "failed to register SPI master\n");
return err;
}
err = clk_prepare_enable(ahb_clk);
if (err)
return err;
rbspi = spi_master_get_devdata(master);
rbspi->base = spi_base;
rbspi->clk = ahb_clk;
platform_set_drvdata(pdev, rbspi);
/* Enable SPI */
rb4xx_write(rbspi, AR71XX_SPI_REG_FS, AR71XX_SPI_FS_GPIO);
return 0;
}
static int rb4xx_spi_remove(struct platform_device *pdev)
{
struct rb4xx_spi *rbspi = platform_get_drvdata(pdev);
clk_disable_unprepare(rbspi->clk);
return 0;
}
static struct platform_driver rb4xx_spi_drv = {
.probe = rb4xx_spi_probe,
.remove = rb4xx_spi_remove,
.driver = {
.name = "rb4xx-spi",
},
};
module_platform_driver(rb4xx_spi_drv);
MODULE_DESCRIPTION("Mikrotik RB4xx SPI controller driver");
MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>");
MODULE_AUTHOR("Bert Vermeulen <bert@biot.com>");
MODULE_LICENSE("GPL v2");
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