spi: loongson: add bus driver for the loongson spi controller

This bus driver supports the Loongson SPI hardware controller in the
Loongson platforms and supports the use DTS and PCI framework to
register SPI device resources.

Signed-off-by: Yinbo Zhu <zhuyinbo@loongson.cn>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Mark Brown <broonie@kernel.org>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20230613075834.5219-3-zhuyinbo@loongson.cn
Signed-off-by: Mark Brown <broonie@kernel.org>

1 files changed, 279 insertions, 0 deletions

diff --git a/drivers/spi/spi-loongson-core.c b/drivers/spi/spi-loongson-core.c
new file mode 100644
index 000000000000..f97800b6fd65
--- /dev/null
+++ b/drivers/spi/spi-loongson-core.c
@@ -0,0 +1,279 @@
+// SPDX-License-Identifier: GPL-2.0+
+// Loongson SPI Support
+// Copyright (C) 2023 Loongson Technology Corporation Limited
+
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/iopoll.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/spi/spi.h>
+
+#include "spi-loongson.h"
+
+static inline void loongson_spi_write_reg(struct loongson_spi *spi, unsigned char reg,
+					  unsigned char data)
+{
+	writeb(data, spi->base + reg);
+}
+
+static inline char loongson_spi_read_reg(struct loongson_spi *spi, unsigned char reg)
+{
+	return readb(spi->base + reg);
+}
+
+static void loongson_spi_set_cs(struct spi_device *spi, bool en)
+{
+	int cs;
+	unsigned char mask = (BIT(4) | BIT(0)) << spi_get_chipselect(spi, 0);
+	unsigned char val = en ? mask :  (BIT(0) << spi_get_chipselect(spi, 0));
+	struct loongson_spi *loongson_spi = spi_controller_get_devdata(spi->controller);
+
+	cs = loongson_spi_read_reg(loongson_spi, LOONGSON_SPI_SFCS_REG) & ~mask;
+	loongson_spi_write_reg(loongson_spi, LOONGSON_SPI_SFCS_REG, val | cs);
+}
+
+static void loongson_spi_set_clk(struct loongson_spi *loongson_spi, unsigned int hz)
+{
+	unsigned char val;
+	unsigned int div, div_tmp;
+	static const char rdiv[12] = {0, 1, 4, 2, 3, 5, 6, 7, 8, 9, 10, 11};
+
+	div = clamp_val(DIV_ROUND_UP_ULL(loongson_spi->clk_rate, hz), 2, 4096);
+	div_tmp = rdiv[fls(div - 1)];
+	loongson_spi->spcr = (div_tmp & GENMASK(1, 0)) >> 0;
+	loongson_spi->sper = (div_tmp & GENMASK(3, 2)) >> 2;
+	val = loongson_spi_read_reg(loongson_spi, LOONGSON_SPI_SPCR_REG);
+	val &= ~GENMASK(1, 0);
+	loongson_spi_write_reg(loongson_spi, LOONGSON_SPI_SPCR_REG, val |
+			       loongson_spi->spcr);
+	val = loongson_spi_read_reg(loongson_spi, LOONGSON_SPI_SPER_REG);
+	val &= ~GENMASK(1, 0);
+	loongson_spi_write_reg(loongson_spi, LOONGSON_SPI_SPER_REG, val |
+			       loongson_spi->sper);
+	loongson_spi->hz = hz;
+}
+
+static void loongson_spi_set_mode(struct loongson_spi *loongson_spi,
+				  struct spi_device *spi)
+{
+	unsigned char val;
+
+	val = loongson_spi_read_reg(loongson_spi, LOONGSON_SPI_SPCR_REG);
+	val &= ~(LOONGSON_SPI_SPCR_CPOL | LOONGSON_SPI_SPCR_CPHA);
+	if (spi->mode & SPI_CPOL)
+		val |= LOONGSON_SPI_SPCR_CPOL;
+	if (spi->mode & SPI_CPHA)
+		val |= LOONGSON_SPI_SPCR_CPHA;
+
+	loongson_spi_write_reg(loongson_spi, LOONGSON_SPI_SPCR_REG, val);
+	loongson_spi->mode |= spi->mode;
+}
+
+static int loongson_spi_update_state(struct loongson_spi *loongson_spi,
+				struct spi_device *spi, struct spi_transfer *t)
+{
+	if (t && loongson_spi->hz != t->speed_hz)
+		loongson_spi_set_clk(loongson_spi, t->speed_hz);
+
+	if ((spi->mode ^ loongson_spi->mode) & SPI_MODE_X_MASK)
+		loongson_spi_set_mode(loongson_spi, spi);
+
+	return 0;
+}
+
+static int loongson_spi_setup(struct spi_device *spi)
+{
+	struct loongson_spi *loongson_spi;
+
+	loongson_spi = spi_controller_get_devdata(spi->controller);
+	if (spi->bits_per_word % 8)
+		return -EINVAL;
+
+	if (spi_get_chipselect(spi, 0) >= spi->controller->num_chipselect)
+		return -EINVAL;
+
+	loongson_spi->hz = 0;
+	loongson_spi_set_cs(spi, true);
+
+	return 0;
+}
+
+static int loongson_spi_write_read_8bit(struct spi_device *spi, const u8 **tx_buf,
+					u8 **rx_buf, unsigned int num)
+{
+	int ret;
+	struct loongson_spi *loongson_spi = spi_controller_get_devdata(spi->controller);
+
+	if (tx_buf && *tx_buf)
+		loongson_spi_write_reg(loongson_spi, LOONGSON_SPI_FIFO_REG, *((*tx_buf)++));
+	else
+		loongson_spi_write_reg(loongson_spi, LOONGSON_SPI_FIFO_REG, 0);
+
+	ret = readb_poll_timeout(loongson_spi->base + LOONGSON_SPI_SPSR_REG,
+				 loongson_spi->spsr, (loongson_spi->spsr &
+				 LOONGSON_SPI_SPSR_RFEMPTY) != LOONGSON_SPI_SPSR_RFEMPTY,
+				 1, USEC_PER_MSEC);
+
+	if (rx_buf && *rx_buf)
+		*(*rx_buf)++ = loongson_spi_read_reg(loongson_spi, LOONGSON_SPI_FIFO_REG);
+	else
+		loongson_spi_read_reg(loongson_spi, LOONGSON_SPI_FIFO_REG);
+
+	return ret;
+}
+
+static int loongson_spi_write_read(struct spi_device *spi, struct spi_transfer *xfer)
+{
+	int ret;
+	unsigned int count;
+	const u8 *tx = xfer->tx_buf;
+	u8 *rx = xfer->rx_buf;
+
+	count = xfer->len;
+	do {
+		ret = loongson_spi_write_read_8bit(spi, &tx, &rx, count);
+		if (ret)
+			break;
+	} while (--count);
+
+	return ret;
+}
+
+static int loongson_spi_prepare_message(struct spi_controller *ctlr, struct spi_message *m)
+{
+	struct loongson_spi *loongson_spi = spi_controller_get_devdata(ctlr);
+
+	loongson_spi->para = loongson_spi_read_reg(loongson_spi, LOONGSON_SPI_PARA_REG);
+	loongson_spi_write_reg(loongson_spi, LOONGSON_SPI_PARA_REG, loongson_spi->para &
+			       ~LOONGSON_SPI_PARA_MEM_EN);
+
+	return 0;
+}
+
+static int loongson_spi_transfer_one(struct spi_controller *ctrl, struct spi_device *spi,
+				     struct spi_transfer *xfer)
+{
+	struct loongson_spi *loongson_spi = spi_controller_get_devdata(spi->controller);
+
+	loongson_spi_update_state(loongson_spi, spi, xfer);
+	if (xfer->len)
+		return loongson_spi_write_read(spi, xfer);
+
+	return 0;
+}
+
+static int loongson_spi_unprepare_message(struct spi_controller *ctrl, struct spi_message *m)
+{
+	struct loongson_spi *loongson_spi = spi_controller_get_devdata(ctrl);
+
+	loongson_spi_write_reg(loongson_spi, LOONGSON_SPI_PARA_REG, loongson_spi->para);
+
+	return 0;
+}
+
+static void loongson_spi_reginit(struct loongson_spi *loongson_spi_dev)
+{
+	unsigned char val;
+
+	val = loongson_spi_read_reg(loongson_spi_dev, LOONGSON_SPI_SPCR_REG);
+	val &= ~LOONGSON_SPI_SPCR_SPE;
+	loongson_spi_write_reg(loongson_spi_dev, LOONGSON_SPI_SPCR_REG, val);
+
+	loongson_spi_write_reg(loongson_spi_dev, LOONGSON_SPI_SPSR_REG,
+			       (LOONGSON_SPI_SPSR_SPIF | LOONGSON_SPI_SPSR_WCOL));
+
+	val = loongson_spi_read_reg(loongson_spi_dev, LOONGSON_SPI_SPCR_REG);
+	val |= LOONGSON_SPI_SPCR_SPE;
+	loongson_spi_write_reg(loongson_spi_dev, LOONGSON_SPI_SPCR_REG, val);
+}
+
+int loongson_spi_init_controller(struct device *dev, void __iomem *regs)
+{
+	struct spi_controller *controller;
+	struct loongson_spi *spi;
+	struct clk *clk;
+
+	controller = devm_spi_alloc_host(dev, sizeof(struct loongson_spi));
+	if (controller == NULL)
+		return -ENOMEM;
+
+	controller->mode_bits = SPI_MODE_X_MASK | SPI_CS_HIGH;
+	controller->setup = loongson_spi_setup;
+	controller->prepare_message = loongson_spi_prepare_message;
+	controller->transfer_one = loongson_spi_transfer_one;
+	controller->unprepare_message = loongson_spi_unprepare_message;
+	controller->set_cs = loongson_spi_set_cs;
+	controller->num_chipselect = 4;
+	device_set_node(&controller->dev, dev_fwnode(dev));
+	dev_set_drvdata(dev, controller);
+
+	spi = spi_controller_get_devdata(controller);
+	spi->base = regs;
+	spi->controller = controller;
+
+	clk = devm_clk_get_optional(dev, NULL);
+	if (IS_ERR(clk))
+		return dev_err_probe(dev, PTR_ERR(clk), "unable to get clock\n");
+
+	spi->clk_rate = clk_get_rate(clk);
+	loongson_spi_reginit(spi);
+
+	spi->mode = 0;
+
+	return devm_spi_register_controller(dev, controller);
+}
+EXPORT_SYMBOL_NS_GPL(loongson_spi_init_controller, SPI_LOONGSON_CORE);
+
+static int __maybe_unused loongson_spi_suspend(struct device *dev)
+{
+	struct loongson_spi *loongson_spi;
+	struct spi_controller *controller;
+
+	controller = dev_get_drvdata(dev);
+	spi_controller_suspend(controller);
+
+	loongson_spi = spi_controller_get_devdata(controller);
+
+	loongson_spi->spcr = loongson_spi_read_reg(loongson_spi, LOONGSON_SPI_SPCR_REG);
+	loongson_spi->sper = loongson_spi_read_reg(loongson_spi, LOONGSON_SPI_SPER_REG);
+	loongson_spi->spsr = loongson_spi_read_reg(loongson_spi, LOONGSON_SPI_SPSR_REG);
+	loongson_spi->para = loongson_spi_read_reg(loongson_spi, LOONGSON_SPI_PARA_REG);
+	loongson_spi->sfcs = loongson_spi_read_reg(loongson_spi, LOONGSON_SPI_SFCS_REG);
+	loongson_spi->timi = loongson_spi_read_reg(loongson_spi, LOONGSON_SPI_TIMI_REG);
+
+	return 0;
+}
+
+static int __maybe_unused loongson_spi_resume(struct device *dev)
+{
+	struct loongson_spi *loongson_spi;
+	struct spi_controller *controller;
+
+	controller = dev_get_drvdata(dev);
+	loongson_spi = spi_controller_get_devdata(controller);
+
+	loongson_spi_write_reg(loongson_spi, LOONGSON_SPI_SPCR_REG, loongson_spi->spcr);
+	loongson_spi_write_reg(loongson_spi, LOONGSON_SPI_SPER_REG, loongson_spi->sper);
+	loongson_spi_write_reg(loongson_spi, LOONGSON_SPI_SPSR_REG, loongson_spi->spsr);
+	loongson_spi_write_reg(loongson_spi, LOONGSON_SPI_PARA_REG, loongson_spi->para);
+	loongson_spi_write_reg(loongson_spi, LOONGSON_SPI_SFCS_REG, loongson_spi->sfcs);
+	loongson_spi_write_reg(loongson_spi, LOONGSON_SPI_TIMI_REG, loongson_spi->timi);
+
+	spi_controller_resume(controller);
+
+	return 0;
+}
+
+const struct dev_pm_ops loongson_spi_dev_pm_ops = {
+	.suspend = loongson_spi_suspend,
+	.resume = loongson_spi_resume,
+};
+EXPORT_SYMBOL_NS_GPL(loongson_spi_dev_pm_ops, SPI_LOONGSON_CORE);
+
+MODULE_DESCRIPTION("Loongson SPI core driver");
+MODULE_LICENSE("GPL");