1 files changed, 306 insertions, 0 deletions

diff --git a/drivers/spi/spi-oc-tiny.c b/drivers/spi/spi-oc-tiny.c
new file mode 100644
index 000000000..38c14c4e4
--- /dev/null
+++ b/drivers/spi/spi-oc-tiny.c
@@ -0,0 +1,306 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * OpenCores tiny SPI master driver
+ *
+ * https://opencores.org/project,tiny_spi
+ *
+ * Copyright (C) 2011 Thomas Chou <thomas@wytron.com.tw>
+ *
+ * Based on spi_s3c24xx.c, which is:
+ * Copyright (c) 2006 Ben Dooks
+ * Copyright (c) 2006 Simtec Electronics
+ *	Ben Dooks <ben@simtec.co.uk>
+ */
+
+#include <linux/interrupt.h>
+#include <linux/errno.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/spi/spi.h>
+#include <linux/spi/spi_bitbang.h>
+#include <linux/spi/spi_oc_tiny.h>
+#include <linux/io.h>
+#include <linux/of.h>
+
+#define DRV_NAME "spi_oc_tiny"
+
+#define TINY_SPI_RXDATA 0
+#define TINY_SPI_TXDATA 4
+#define TINY_SPI_STATUS 8
+#define TINY_SPI_CONTROL 12
+#define TINY_SPI_BAUD 16
+
+#define TINY_SPI_STATUS_TXE 0x1
+#define TINY_SPI_STATUS_TXR 0x2
+
+struct tiny_spi {
+	/* bitbang has to be first */
+	struct spi_bitbang bitbang;
+	struct completion done;
+
+	void __iomem *base;
+	int irq;
+	unsigned int freq;
+	unsigned int baudwidth;
+	unsigned int baud;
+	unsigned int speed_hz;
+	unsigned int mode;
+	unsigned int len;
+	unsigned int txc, rxc;
+	const u8 *txp;
+	u8 *rxp;
+};
+
+static inline struct tiny_spi *tiny_spi_to_hw(struct spi_device *sdev)
+{
+	return spi_master_get_devdata(sdev->master);
+}
+
+static unsigned int tiny_spi_baud(struct spi_device *spi, unsigned int hz)
+{
+	struct tiny_spi *hw = tiny_spi_to_hw(spi);
+
+	return min(DIV_ROUND_UP(hw->freq, hz * 2), (1U << hw->baudwidth)) - 1;
+}
+
+static int tiny_spi_setup_transfer(struct spi_device *spi,
+				   struct spi_transfer *t)
+{
+	struct tiny_spi *hw = tiny_spi_to_hw(spi);
+	unsigned int baud = hw->baud;
+
+	if (t) {
+		if (t->speed_hz && t->speed_hz != hw->speed_hz)
+			baud = tiny_spi_baud(spi, t->speed_hz);
+	}
+	writel(baud, hw->base + TINY_SPI_BAUD);
+	writel(hw->mode, hw->base + TINY_SPI_CONTROL);
+	return 0;
+}
+
+static int tiny_spi_setup(struct spi_device *spi)
+{
+	struct tiny_spi *hw = tiny_spi_to_hw(spi);
+
+	if (spi->max_speed_hz != hw->speed_hz) {
+		hw->speed_hz = spi->max_speed_hz;
+		hw->baud = tiny_spi_baud(spi, hw->speed_hz);
+	}
+	hw->mode = spi->mode & SPI_MODE_X_MASK;
+	return 0;
+}
+
+static inline void tiny_spi_wait_txr(struct tiny_spi *hw)
+{
+	while (!(readb(hw->base + TINY_SPI_STATUS) &
+		 TINY_SPI_STATUS_TXR))
+		cpu_relax();
+}
+
+static inline void tiny_spi_wait_txe(struct tiny_spi *hw)
+{
+	while (!(readb(hw->base + TINY_SPI_STATUS) &
+		 TINY_SPI_STATUS_TXE))
+		cpu_relax();
+}
+
+static int tiny_spi_txrx_bufs(struct spi_device *spi, struct spi_transfer *t)
+{
+	struct tiny_spi *hw = tiny_spi_to_hw(spi);
+	const u8 *txp = t->tx_buf;
+	u8 *rxp = t->rx_buf;
+	unsigned int i;
+
+	if (hw->irq >= 0) {
+		/* use interrupt driven data transfer */
+		hw->len = t->len;
+		hw->txp = t->tx_buf;
+		hw->rxp = t->rx_buf;
+		hw->txc = 0;
+		hw->rxc = 0;
+
+		/* send the first byte */
+		if (t->len > 1) {
+			writeb(hw->txp ? *hw->txp++ : 0,
+			       hw->base + TINY_SPI_TXDATA);
+			hw->txc++;
+			writeb(hw->txp ? *hw->txp++ : 0,
+			       hw->base + TINY_SPI_TXDATA);
+			hw->txc++;
+			writeb(TINY_SPI_STATUS_TXR, hw->base + TINY_SPI_STATUS);
+		} else {
+			writeb(hw->txp ? *hw->txp++ : 0,
+			       hw->base + TINY_SPI_TXDATA);
+			hw->txc++;
+			writeb(TINY_SPI_STATUS_TXE, hw->base + TINY_SPI_STATUS);
+		}
+
+		wait_for_completion(&hw->done);
+	} else {
+		/* we need to tighten the transfer loop */
+		writeb(txp ? *txp++ : 0, hw->base + TINY_SPI_TXDATA);
+		for (i = 1; i < t->len; i++) {
+			writeb(txp ? *txp++ : 0, hw->base + TINY_SPI_TXDATA);
+
+			if (rxp || (i != t->len - 1))
+				tiny_spi_wait_txr(hw);
+			if (rxp)
+				*rxp++ = readb(hw->base + TINY_SPI_TXDATA);
+		}
+		tiny_spi_wait_txe(hw);
+		if (rxp)
+			*rxp++ = readb(hw->base + TINY_SPI_RXDATA);
+	}
+
+	return t->len;
+}
+
+static irqreturn_t tiny_spi_irq(int irq, void *dev)
+{
+	struct tiny_spi *hw = dev;
+
+	writeb(0, hw->base + TINY_SPI_STATUS);
+	if (hw->rxc + 1 == hw->len) {
+		if (hw->rxp)
+			*hw->rxp++ = readb(hw->base + TINY_SPI_RXDATA);
+		hw->rxc++;
+		complete(&hw->done);
+	} else {
+		if (hw->rxp)
+			*hw->rxp++ = readb(hw->base + TINY_SPI_TXDATA);
+		hw->rxc++;
+		if (hw->txc < hw->len) {
+			writeb(hw->txp ? *hw->txp++ : 0,
+			       hw->base + TINY_SPI_TXDATA);
+			hw->txc++;
+			writeb(TINY_SPI_STATUS_TXR,
+			       hw->base + TINY_SPI_STATUS);
+		} else {
+			writeb(TINY_SPI_STATUS_TXE,
+			       hw->base + TINY_SPI_STATUS);
+		}
+	}
+	return IRQ_HANDLED;
+}
+
+#ifdef CONFIG_OF
+#include <linux/of_gpio.h>
+
+static int tiny_spi_of_probe(struct platform_device *pdev)
+{
+	struct tiny_spi *hw = platform_get_drvdata(pdev);
+	struct device_node *np = pdev->dev.of_node;
+	u32 val;
+
+	if (!np)
+		return 0;
+	hw->bitbang.master->dev.of_node = pdev->dev.of_node;
+	if (!of_property_read_u32(np, "clock-frequency", &val))
+		hw->freq = val;
+	if (!of_property_read_u32(np, "baud-width", &val))
+		hw->baudwidth = val;
+	return 0;
+}
+#else /* !CONFIG_OF */
+static int tiny_spi_of_probe(struct platform_device *pdev)
+{
+	return 0;
+}
+#endif /* CONFIG_OF */
+
+static int tiny_spi_probe(struct platform_device *pdev)
+{
+	struct tiny_spi_platform_data *platp = dev_get_platdata(&pdev->dev);
+	struct tiny_spi *hw;
+	struct spi_master *master;
+	int err = -ENODEV;
+
+	master = spi_alloc_master(&pdev->dev, sizeof(struct tiny_spi));
+	if (!master)
+		return err;
+
+	/* setup the master state. */
+	master->bus_num = pdev->id;
+	master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH;
+	master->setup = tiny_spi_setup;
+	master->use_gpio_descriptors = true;
+
+	hw = spi_master_get_devdata(master);
+	platform_set_drvdata(pdev, hw);
+
+	/* setup the state for the bitbang driver */
+	hw->bitbang.master = master;
+	hw->bitbang.setup_transfer = tiny_spi_setup_transfer;
+	hw->bitbang.txrx_bufs = tiny_spi_txrx_bufs;
+
+	/* find and map our resources */
+	hw->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(hw->base)) {
+		err = PTR_ERR(hw->base);
+		goto exit;
+	}
+	/* irq is optional */
+	hw->irq = platform_get_irq(pdev, 0);
+	if (hw->irq >= 0) {
+		init_completion(&hw->done);
+		err = devm_request_irq(&pdev->dev, hw->irq, tiny_spi_irq, 0,
+				       pdev->name, hw);
+		if (err)
+			goto exit;
+	}
+	/* find platform data */
+	if (platp) {
+		hw->freq = platp->freq;
+		hw->baudwidth = platp->baudwidth;
+	} else {
+		err = tiny_spi_of_probe(pdev);
+		if (err)
+			goto exit;
+	}
+
+	/* register our spi controller */
+	err = spi_bitbang_start(&hw->bitbang);
+	if (err)
+		goto exit;
+	dev_info(&pdev->dev, "base %p, irq %d\n", hw->base, hw->irq);
+
+	return 0;
+
+exit:
+	spi_master_put(master);
+	return err;
+}
+
+static int tiny_spi_remove(struct platform_device *pdev)
+{
+	struct tiny_spi *hw = platform_get_drvdata(pdev);
+	struct spi_master *master = hw->bitbang.master;
+
+	spi_bitbang_stop(&hw->bitbang);
+	spi_master_put(master);
+	return 0;
+}
+
+#ifdef CONFIG_OF
+static const struct of_device_id tiny_spi_match[] = {
+	{ .compatible = "opencores,tiny-spi-rtlsvn2", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, tiny_spi_match);
+#endif /* CONFIG_OF */
+
+static struct platform_driver tiny_spi_driver = {
+	.probe = tiny_spi_probe,
+	.remove = tiny_spi_remove,
+	.driver = {
+		.name = DRV_NAME,
+		.pm = NULL,
+		.of_match_table = of_match_ptr(tiny_spi_match),
+	},
+};
+module_platform_driver(tiny_spi_driver);
+
+MODULE_DESCRIPTION("OpenCores tiny SPI driver");
+MODULE_AUTHOR("Thomas Chou <thomas@wytron.com.tw>");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:" DRV_NAME);