[v4,2/2] spi: realtek-rtl: Add support for Realtek RTL838x/RTL839x SoC SPI controllers

diff --git a/MAINTAINERS b/MAINTAINERS
index ad0e34bf8453..c6cb954e5ecf 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -15048,6 +15048,12 @@  F:	Documentation/devicetree/bindings/net/dsa/realtek-smi.txt
 F:	drivers/net/dsa/realtek-smi*
 F:	drivers/net/dsa/rtl83*
 
+REALTEK RTL83XX SPI DRIVER
+M:	Bert Vermeulen <bert@biot.com>
+M:	Birger Koblitz <mail@birger-koblitz.de>
+S:	Maintained
+F:	drivers/spi/spi-realtek-rtl.c
+
 REALTEK WIRELESS DRIVER (rtlwifi family)
 M:	Ping-Ke Shih <pkshih@realtek.com>
 L:	linux-wireless@vger.kernel.org
diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
index 6fea5821662e..182adef17013 100644
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -94,6 +94,7 @@  obj-$(CONFIG_SPI_QCOM_QSPI)		+= spi-qcom-qspi.o
 obj-$(CONFIG_SPI_QUP)			+= spi-qup.o
 obj-$(CONFIG_SPI_ROCKCHIP)		+= spi-rockchip.o
 obj-$(CONFIG_SPI_RB4XX)			+= spi-rb4xx.o
+obj-$(CONFIG_MACH_REALTEK_RTL)		+= spi-realtek-rtl.o
 obj-$(CONFIG_SPI_RPCIF)			+= spi-rpc-if.o
 obj-$(CONFIG_SPI_RSPI)			+= spi-rspi.o
 obj-$(CONFIG_SPI_S3C24XX)		+= spi-s3c24xx-hw.o
diff --git a/drivers/spi/spi-realtek-rtl.c b/drivers/spi/spi-realtek-rtl.c
new file mode 100644
index 000000000000..c46894c6797f
--- /dev/null
+++ b/drivers/spi/spi-realtek-rtl.c
@@ -0,0 +1,206 @@ 
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/mod_devicetable.h>
+#include <linux/spi/spi.h>
+
+struct rtspi {
+	void __iomem *base;
+};
+
+/* SPI Flash Configuration Register */
+#define RTL_SPI_SFCR			0x00
+#define RTL_SPI_SFCR_RBO		BIT(28)
+#define RTL_SPI_SFCR_WBO		BIT(27)
+
+/* SPI Flash Control and Status Register */
+#define RTL_SPI_SFCSR			0x08
+#define RTL_SPI_SFCSR_CSB0		BIT(31)
+#define RTL_SPI_SFCSR_CSB1		BIT(30)
+#define RTL_SPI_SFCSR_RDY		BIT(27)
+#define RTL_SPI_SFCSR_CS		BIT(24)
+#define RTL_SPI_SFCSR_LEN_MASK		~(0x03 << 28)
+#define RTL_SPI_SFCSR_LEN1		(0x00 << 28)
+#define RTL_SPI_SFCSR_LEN4		(0x03 << 28)
+
+/* SPI Flash Data Register */
+#define RTL_SPI_SFDR			0x0c
+
+#define REG(x)		(rtspi->base + x)
+
+
+static void rt_set_cs(struct spi_device *spi, bool active)
+{
+	struct rtspi *rtspi = spi_controller_get_devdata(spi->controller);
+	u32 value;
+
+	/* CS0 bit is active low */
+	value = readl(REG(RTL_SPI_SFCSR));
+	if (active)
+		value |= RTL_SPI_SFCSR_CSB0;
+	else
+		value &= ~RTL_SPI_SFCSR_CSB0;
+	writel(value, REG(RTL_SPI_SFCSR));
+}
+
+static void set_size(struct rtspi *rtspi, int size)
+{
+	u32 value;
+
+	value = readl(REG(RTL_SPI_SFCSR));
+	value &= RTL_SPI_SFCSR_LEN_MASK;
+	if (size == 4)
+		value |= RTL_SPI_SFCSR_LEN4;
+	else if (size == 1)
+		value |= RTL_SPI_SFCSR_LEN1;
+	writel(value, REG(RTL_SPI_SFCSR));
+}
+
+static inline void wait_ready(struct rtspi *rtspi)
+{
+	while (!(readl(REG(RTL_SPI_SFCSR)) & RTL_SPI_SFCSR_RDY))
+		cpu_relax();
+}
+static void send4(struct rtspi *rtspi, const u32 *buf)
+{
+	wait_ready(rtspi);
+	set_size(rtspi, 4);
+	writel(*buf, REG(RTL_SPI_SFDR));
+}
+
+static void send1(struct rtspi *rtspi, const u8 *buf)
+{
+	wait_ready(rtspi);
+	set_size(rtspi, 1);
+	writel(buf[0] << 24, REG(RTL_SPI_SFDR));
+}
+
+static void rcv4(struct rtspi *rtspi, u32 *buf)
+{
+	wait_ready(rtspi);
+	set_size(rtspi, 4);
+	*buf = readl(REG(RTL_SPI_SFDR));
+}
+
+static void rcv1(struct rtspi *rtspi, u8 *buf)
+{
+	wait_ready(rtspi);
+	set_size(rtspi, 1);
+	*buf = readl(REG(RTL_SPI_SFDR)) >> 24;
+}
+
+static int transfer_one(struct spi_controller *ctrl, struct spi_device *spi,
+			struct spi_transfer *xfer)
+{
+	struct rtspi *rtspi = spi_controller_get_devdata(ctrl);
+	void *rx_buf;
+	const void *tx_buf;
+	int cnt;
+
+	tx_buf = xfer->tx_buf;
+	rx_buf = xfer->rx_buf;
+	cnt = xfer->len;
+	if (tx_buf) {
+		while (cnt >= 4) {
+			send4(rtspi, tx_buf);
+			tx_buf += 4;
+			cnt -= 4;
+		}
+		while (cnt) {
+			send1(rtspi, tx_buf);
+			tx_buf++;
+			cnt--;
+		}
+	} else if (rx_buf) {
+		while (cnt >= 4) {
+			rcv4(rtspi, rx_buf);
+			rx_buf += 4;
+			cnt -= 4;
+		}
+		while (cnt) {
+			rcv1(rtspi, rx_buf);
+			rx_buf++;
+			cnt--;
+		}
+	}
+
+	spi_finalize_current_transfer(ctrl);
+
+	return 0;
+}
+
+static void init_hw(struct rtspi *rtspi)
+{
+	u32 value;
+
+	/* Turn on big-endian byte ordering */
+	value = readl(REG(RTL_SPI_SFCR));
+	value |= RTL_SPI_SFCR_RBO | RTL_SPI_SFCR_WBO;
+	writel(value, REG(RTL_SPI_SFCR));
+
+	value = readl(REG(RTL_SPI_SFCSR));
+	/* Permanently disable CS1, since it's never used */
+	value |= RTL_SPI_SFCSR_CSB1;
+	/* Select CS0 for use */
+	value &= RTL_SPI_SFCSR_CS;
+	writel(value, REG(RTL_SPI_SFCSR));
+}
+
+static int realtek_rtl_spi_probe(struct platform_device *pdev)
+{
+	struct spi_controller *ctrl;
+	struct rtspi *rtspi;
+	int err;
+
+	ctrl = devm_spi_alloc_master(&pdev->dev, sizeof(*rtspi));
+	if (!ctrl) {
+		dev_err(&pdev->dev, "Error allocating SPI controller\n");
+		return -ENOMEM;
+	}
+	platform_set_drvdata(pdev, ctrl);
+	rtspi = spi_controller_get_devdata(ctrl);
+
+	rtspi->base = devm_platform_get_and_ioremap_resource(pdev, 0, NULL);
+	if (IS_ERR(rtspi->base)) {
+		dev_err(&pdev->dev, "Could not map SPI register address");
+		return -ENOMEM;
+	}
+
+	init_hw(rtspi);
+
+	ctrl->dev.of_node = pdev->dev.of_node;
+	ctrl->flags = SPI_CONTROLLER_HALF_DUPLEX;
+	ctrl->set_cs = rt_set_cs;
+	ctrl->transfer_one = transfer_one;
+
+	err = devm_spi_register_controller(&pdev->dev, ctrl);
+	if (err) {
+		dev_err(&pdev->dev, "Could not register SPI controller\n");
+		return -ENODEV;
+	}
+
+	return 0;
+}
+
+
+static const struct of_device_id realtek_rtl_spi_of_ids[] = {
+	{ .compatible = "realtek,rtl838x-spi" },
+	{ .compatible = "realtek,rtl839x-spi" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, realtek_rtl_spi_of_ids);
+
+static struct platform_driver realtek_rtl_spi_driver = {
+	.probe = realtek_rtl_spi_probe,
+	.driver = {
+		.name = "realtek-rtl83xx-spi",
+		.of_match_table = realtek_rtl_spi_of_ids,
+	},
+};
+
+module_platform_driver(realtek_rtl_spi_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Bert Vermeulen <bert@biot.com>");
+MODULE_DESCRIPTION("Realtek RTL SPI driver");