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// SPDX-License-Identifier: GPL-2.0-only
/*
* SPI controller driver for the Atheros AR71XX/AR724X/AR913X SoCs
*
* Copyright (C) 2009-2011 Gabor Juhos <juhosg@openwrt.org>
*
* This driver has been based on the spi-gpio.c:
* Copyright (C) 2006,2008 David Brownell
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/delay.h>
#include <linux/spinlock.h>
#include <linux/platform_device.h>
#include <linux/io.h>
#include <linux/spi/spi.h>
#include <linux/spi/spi-mem.h>
#include <linux/spi/spi_bitbang.h>
#include <linux/bitops.h>
#include <linux/clk.h>
#include <linux/err.h>
#define DRV_NAME "ath79-spi"
#define ATH79_SPI_RRW_DELAY_FACTOR 12000
#define MHZ (1000 * 1000)
#define AR71XX_SPI_REG_FS 0x00 /* Function Select */
#define AR71XX_SPI_REG_CTRL 0x04 /* SPI Control */
#define AR71XX_SPI_REG_IOC 0x08 /* SPI I/O Control */
#define AR71XX_SPI_REG_RDS 0x0c /* Read Data Shift */
#define AR71XX_SPI_FS_GPIO BIT(0) /* Enable GPIO mode */
#define AR71XX_SPI_IOC_DO BIT(0) /* Data Out pin */
#define AR71XX_SPI_IOC_CLK BIT(8) /* CLK pin */
#define AR71XX_SPI_IOC_CS(n) BIT(16 + (n))
struct ath79_spi {
struct spi_bitbang bitbang;
u32 ioc_base;
u32 reg_ctrl;
void __iomem *base;
struct clk *clk;
unsigned int rrw_delay;
};
static inline u32 ath79_spi_rr(struct ath79_spi *sp, unsigned int reg)
{
return ioread32(sp->base + reg);
}
static inline void ath79_spi_wr(struct ath79_spi *sp, unsigned int reg, u32 val)
{
iowrite32(val, sp->base + reg);
}
static inline struct ath79_spi *ath79_spidev_to_sp(struct spi_device *spi)
{
return spi_controller_get_devdata(spi->controller);
}
static inline void ath79_spi_delay(struct ath79_spi *sp, unsigned int nsecs)
{
if (nsecs > sp->rrw_delay)
ndelay(nsecs - sp->rrw_delay);
}
static void ath79_spi_chipselect(struct spi_device *spi, int is_active)
{
struct ath79_spi *sp = ath79_spidev_to_sp(spi);
int cs_high = (spi->mode & SPI_CS_HIGH) ? is_active : !is_active;
u32 cs_bit = AR71XX_SPI_IOC_CS(spi_get_chipselect(spi, 0));
if (cs_high)
sp->ioc_base |= cs_bit;
else
sp->ioc_base &= ~cs_bit;
ath79_spi_wr(sp, AR71XX_SPI_REG_IOC, sp->ioc_base);
}
static void ath79_spi_enable(struct ath79_spi *sp)
{
/* enable GPIO mode */
ath79_spi_wr(sp, AR71XX_SPI_REG_FS, AR71XX_SPI_FS_GPIO);
/* save CTRL register */
sp->reg_ctrl = ath79_spi_rr(sp, AR71XX_SPI_REG_CTRL);
sp->ioc_base = ath79_spi_rr(sp, AR71XX_SPI_REG_IOC);
/* clear clk and mosi in the base state */
sp->ioc_base &= ~(AR71XX_SPI_IOC_DO | AR71XX_SPI_IOC_CLK);
/* TODO: setup speed? */
ath79_spi_wr(sp, AR71XX_SPI_REG_CTRL, 0x43);
}
static void ath79_spi_disable(struct ath79_spi *sp)
{
/* restore CTRL register */
ath79_spi_wr(sp, AR71XX_SPI_REG_CTRL, sp->reg_ctrl);
/* disable GPIO mode */
ath79_spi_wr(sp, AR71XX_SPI_REG_FS, 0);
}
static u32 ath79_spi_txrx_mode0(struct spi_device *spi, unsigned int nsecs,
u32 word, u8 bits, unsigned flags)
{
struct ath79_spi *sp = ath79_spidev_to_sp(spi);
u32 ioc = sp->ioc_base;
/* clock starts at inactive polarity */
for (word <<= (32 - bits); likely(bits); bits--) {
u32 out;
if (word & (1 << 31))
out = ioc | AR71XX_SPI_IOC_DO;
else
out = ioc & ~AR71XX_SPI_IOC_DO;
/* setup MSB (to target) on trailing edge */
ath79_spi_wr(sp, AR71XX_SPI_REG_IOC, out);
ath79_spi_delay(sp, nsecs);
ath79_spi_wr(sp, AR71XX_SPI_REG_IOC, out | AR71XX_SPI_IOC_CLK);
ath79_spi_delay(sp, nsecs);
if (bits == 1)
ath79_spi_wr(sp, AR71XX_SPI_REG_IOC, out);
word <<= 1;
}
return ath79_spi_rr(sp, AR71XX_SPI_REG_RDS);
}
static int ath79_exec_mem_op(struct spi_mem *mem,
const struct spi_mem_op *op)
{
struct ath79_spi *sp = ath79_spidev_to_sp(mem->spi);
/* Ensures that reading is performed on device connected to hardware cs0 */
if (spi_get_chipselect(mem->spi, 0) || spi_get_csgpiod(mem->spi, 0))
return -ENOTSUPP;
/* Only use for fast-read op. */
if (op->cmd.opcode != 0x0b || op->data.dir != SPI_MEM_DATA_IN ||
op->addr.nbytes != 3 || op->dummy.nbytes != 1)
return -ENOTSUPP;
/* disable GPIO mode */
ath79_spi_wr(sp, AR71XX_SPI_REG_FS, 0);
memcpy_fromio(op->data.buf.in, sp->base + op->addr.val, op->data.nbytes);
/* enable GPIO mode */
ath79_spi_wr(sp, AR71XX_SPI_REG_FS, AR71XX_SPI_FS_GPIO);
/* restore IOC register */
ath79_spi_wr(sp, AR71XX_SPI_REG_IOC, sp->ioc_base);
return 0;
}
static const struct spi_controller_mem_ops ath79_mem_ops = {
.exec_op = ath79_exec_mem_op,
};
static int ath79_spi_probe(struct platform_device *pdev)
{
struct spi_controller *host;
struct ath79_spi *sp;
unsigned long rate;
int ret;
host = spi_alloc_host(&pdev->dev, sizeof(*sp));
if (host == NULL) {
dev_err(&pdev->dev, "failed to allocate spi host\n");
return -ENOMEM;
}
sp = spi_controller_get_devdata(host);
host->dev.of_node = pdev->dev.of_node;
platform_set_drvdata(pdev, sp);
host->use_gpio_descriptors = true;
host->bits_per_word_mask = SPI_BPW_RANGE_MASK(1, 32);
host->flags = SPI_CONTROLLER_GPIO_SS;
host->num_chipselect = 3;
host->mem_ops = &ath79_mem_ops;
sp->bitbang.master = host;
sp->bitbang.chipselect = ath79_spi_chipselect;
sp->bitbang.txrx_word[SPI_MODE_0] = ath79_spi_txrx_mode0;
sp->bitbang.flags = SPI_CS_HIGH;
sp->base = devm_platform_ioremap_resource(pdev, 0);
if (IS_ERR(sp->base)) {
ret = PTR_ERR(sp->base);
goto err_put_host;
}
sp->clk = devm_clk_get(&pdev->dev, "ahb");
if (IS_ERR(sp->clk)) {
ret = PTR_ERR(sp->clk);
goto err_put_host;
}
ret = clk_prepare_enable(sp->clk);
if (ret)
goto err_put_host;
rate = DIV_ROUND_UP(clk_get_rate(sp->clk), MHZ);
if (!rate) {
ret = -EINVAL;
goto err_clk_disable;
}
sp->rrw_delay = ATH79_SPI_RRW_DELAY_FACTOR / rate;
dev_dbg(&pdev->dev, "register read/write delay is %u nsecs\n",
sp->rrw_delay);
ath79_spi_enable(sp);
ret = spi_bitbang_start(&sp->bitbang);
if (ret)
goto err_disable;
return 0;
err_disable:
ath79_spi_disable(sp);
err_clk_disable:
clk_disable_unprepare(sp->clk);
err_put_host:
spi_controller_put(host);
return ret;
}
static void ath79_spi_remove(struct platform_device *pdev)
{
struct ath79_spi *sp = platform_get_drvdata(pdev);
spi_bitbang_stop(&sp->bitbang);
ath79_spi_disable(sp);
clk_disable_unprepare(sp->clk);
spi_controller_put(sp->bitbang.master);
}
static void ath79_spi_shutdown(struct platform_device *pdev)
{
ath79_spi_remove(pdev);
}
static const struct of_device_id ath79_spi_of_match[] = {
{ .compatible = "qca,ar7100-spi", },
{ },
};
MODULE_DEVICE_TABLE(of, ath79_spi_of_match);
static struct platform_driver ath79_spi_driver = {
.probe = ath79_spi_probe,
.remove_new = ath79_spi_remove,
.shutdown = ath79_spi_shutdown,
.driver = {
.name = DRV_NAME,
.of_match_table = ath79_spi_of_match,
},
};
module_platform_driver(ath79_spi_driver);
MODULE_DESCRIPTION("SPI controller driver for Atheros AR71XX/AR724X/AR913X");
MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:" DRV_NAME);
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