1 files changed, 277 insertions, 0 deletions
diff --git a/drivers/spi/spi-ath79.c b/drivers/spi/spi-ath79.c
new file mode 100644
index 000000000..607e7a49f
--- /dev/null
+++ b/drivers/spi/spi-ath79.c
@@ -0,0 +1,277 @@
+// 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_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_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 (mem->spi->chip_select || mem->spi->cs_gpiod)
+		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_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;
+	master->mem_ops = &ath79_mem_ops;
+
+	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);