linux/drivers/spi/spi-ath79.c
David Bauer ab053f48f9
spi: ath79: set number of chipselect lines
All chipsets from AR7100 up to QCA9563 have three dedicated chipselect
lines for the integrated SPI controller. Set the number of chipselect
lines available on the controller to this value.

Signed-off-by: David Bauer <mail@david-bauer.net>
Link: https://lore.kernel.org/r/20210522074453.39299-2-mail@david-bauer.net
Signed-off-by: Mark Brown <broonie@kernel.org>
2021-05-24 09:51:38 +01:00

244 lines
5.9 KiB
C

// 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_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_master_get_devdata(spi->master);
}
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->chip_select);
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 slave) 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_spi_probe(struct platform_device *pdev)
{
struct spi_master *master;
struct ath79_spi *sp;
unsigned long rate;
int ret;
master = spi_alloc_master(&pdev->dev, sizeof(*sp));
if (master == NULL) {
dev_err(&pdev->dev, "failed to allocate spi master\n");
return -ENOMEM;
}
sp = spi_master_get_devdata(master);
master->dev.of_node = pdev->dev.of_node;
platform_set_drvdata(pdev, sp);
master->use_gpio_descriptors = true;
master->bits_per_word_mask = SPI_BPW_RANGE_MASK(1, 32);
master->flags = SPI_MASTER_GPIO_SS;
master->num_chipselect = 3;
sp->bitbang.master = master;
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_master;
}
sp->clk = devm_clk_get(&pdev->dev, "ahb");
if (IS_ERR(sp->clk)) {
ret = PTR_ERR(sp->clk);
goto err_put_master;
}
ret = clk_prepare_enable(sp->clk);
if (ret)
goto err_put_master;
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_master:
spi_master_put(sp->bitbang.master);
return ret;
}
static int 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_master_put(sp->bitbang.master);
return 0;
}
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 = 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);