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 <[e-mail]>
Cc: Andy Shevchenko <[e-mail]>
Cc: Mark Brown <[e-mail]>
Reviewed-by: Andy Shevchenko <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Mark Brown <[e-mail]>

MAINTAINERS

···
 L:	[e-mail]
 S:	Maintained
 F:	Documentation/devicetree/bindings/spi/loongson,ls2k-spi.yaml
+F:	drivers/spi/spi-loongson-core.c
+F:	drivers/spi/spi-loongson-pci.c
+F:	drivers/spi/spi-loongson-plat.c
+F:	drivers/spi/spi-loongson.h
 
 LOONGSON-2 SOC SERIES GUTS DRIVER
 M:	Yinbo Zhu <[e-mail]>

drivers/spi/Kconfig

···
 	  which interfaces to an LM70 temperature sensor using
 	  a parallel port.
 
+config SPI_LOONGSON_CORE
+	tristate
+	depends on LOONGARCH || COMPILE_TEST
+
+config SPI_LOONGSON_PCI
+	tristate "Loongson SPI Controller PCI Driver Support"
+	select SPI_LOONGSON_CORE
+	depends on PCI && (LOONGARCH || COMPILE_TEST)
+	help
+	  This bus driver supports the Loongson SPI hardware controller in
+	  the Loongson platforms and supports to use PCI framework to
+	  register SPI device resources.
+	  Say Y or M here if you want to use the SPI controller on
+	  Loongson platform.
+
+config SPI_LOONGSON_PLATFORM
+	tristate "Loongson SPI Controller Platform Driver Support"
+	select SPI_LOONGSON_CORE
+	depends on OF && (LOONGARCH || COMPILE_TEST)
+	help
+	  This bus driver supports the Loongson SPI hardware controller in
+	  the Loongson platforms and supports to use DTS framework to
+	  register SPI device resources.
+	  Say Y or M here if you want to use the SPI controller on
+	  Loongson platform.
+
 config SPI_LP8841_RTC
 	tristate "ICP DAS LP-8841 SPI Controller for RTC"
 	depends on MACH_PXA27X_DT || COMPILE_TEST

drivers/spi/Makefile

···
 obj-$(CONFIG_SPI_LANTIQ_SSC)		+= spi-lantiq-ssc.o
 obj-$(CONFIG_SPI_JCORE)			+= spi-jcore.o
 obj-$(CONFIG_SPI_LM70_LLP)		+= spi-lm70llp.o
+obj-$(CONFIG_SPI_LOONGSON_CORE)		+= spi-loongson-core.o
+obj-$(CONFIG_SPI_LOONGSON_PCI)		+= spi-loongson-pci.o
+obj-$(CONFIG_SPI_LOONGSON_PLATFORM)	+= spi-loongson-plat.o
 obj-$(CONFIG_SPI_LP8841_RTC)		+= spi-lp8841-rtc.o
 obj-$(CONFIG_SPI_MESON_SPICC)		+= spi-meson-spicc.o
 obj-$(CONFIG_SPI_MESON_SPIFC)		+= spi-meson-spifc.o

drivers/spi/spi-loongson-core.c

···
+// 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");

drivers/spi/spi-loongson-pci.c

···
+// SPDX-License-Identifier: GPL-2.0+
+// PCI interface driver for Loongson SPI Support
+// Copyright (C) 2023 Loongson Technology Corporation Limited
+
+#include <linux/mod_devicetable.h>
+#include <linux/pci.h>
+
+#include "spi-loongson.h"
+
+static int loongson_spi_pci_register(struct pci_dev *pdev,
+			const struct pci_device_id *ent)
+{
+	int ret;
+	void __iomem *reg_base;
+	struct device *dev = &pdev->dev;
+	int pci_bar = 0;
+
+	ret = pcim_enable_device(pdev);
+	if (ret < 0)
+		return dev_err_probe(dev, ret, "cannot enable pci device\n");
+
+	ret = pcim_iomap_regions(pdev, BIT(pci_bar), pci_name(pdev));
+	if (ret)
+		return dev_err_probe(dev, ret, "failed to request and remap memory\n");
+
+	reg_base = pcim_iomap_table(pdev)[pci_bar];
+
+	ret = loongson_spi_init_controller(dev, reg_base);
+	if (ret)
+		return dev_err_probe(dev, ret, "failed to initialize controller\n");
+
+	return 0;
+}
+
+static struct pci_device_id loongson_spi_devices[] = {
+	{ PCI_DEVICE(PCI_VENDOR_ID_LOONGSON, 0x7a0b) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_LOONGSON, 0x7a1b) },
+	{ }
+};
+MODULE_DEVICE_TABLE(pci, loongson_spi_devices);
+
+static struct pci_driver loongson_spi_pci_driver = {
+	.name       = "loongson-spi-pci",
+	.id_table   = loongson_spi_devices,
+	.probe      = loongson_spi_pci_register,
+	.driver	= {
+		.bus = &pci_bus_type,
+		.pm = &loongson_spi_dev_pm_ops,
+	},
+};
+module_pci_driver(loongson_spi_pci_driver);
+
+MODULE_DESCRIPTION("Loongson spi pci driver");
+MODULE_LICENSE("GPL");
+MODULE_IMPORT_NS(SPI_LOONGSON_CORE);

drivers/spi/spi-loongson-plat.c

···
+// SPDX-License-Identifier: GPL-2.0+
+// Platform driver for Loongson SPI Support
+// Copyright (C) 2023 Loongson Technology Corporation Limited
+
+#include <linux/err.h>
+#include <linux/mod_devicetable.h>
+#include <linux/platform_device.h>
+
+#include "spi-loongson.h"
+
+static int loongson_spi_platform_probe(struct platform_device *pdev)
+{
+	int ret;
+	void __iomem *reg_base;
+	struct device *dev = &pdev->dev;
+
+	reg_base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(reg_base))
+		return PTR_ERR(reg_base);
+
+	ret = loongson_spi_init_controller(dev, reg_base);
+	if (ret)
+		return dev_err_probe(dev, ret, "failed to initialize controller\n");
+
+	return 0;
+}
+
+static const struct of_device_id loongson_spi_id_table[] = {
+	{ .compatible = "loongson,ls2k1000-spi" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, loongson_spi_id_table);
+
+static struct platform_driver loongson_spi_plat_driver = {
+	.probe = loongson_spi_platform_probe,
+	.driver	= {
+		.name	= "loongson-spi",
+		.bus = &platform_bus_type,
+		.pm = &loongson_spi_dev_pm_ops,
+		.of_match_table = loongson_spi_id_table,
+	},
+};
+module_platform_driver(loongson_spi_plat_driver);
+
+MODULE_DESCRIPTION("Loongson spi platform driver");
+MODULE_LICENSE("GPL");
+MODULE_IMPORT_NS(SPI_LOONGSON_CORE);

drivers/spi/spi-loongson.h

···
+/* SPDX-License-Identifier: GPL-2.0+ */
+/* Header File for Loongson SPI Driver. */
+/* Copyright (C) 2023 Loongson Technology Corporation Limited */
+
+#ifndef __LINUX_SPI_LOONGSON_H
+#define __LINUX_SPI_LOONGSON_H
+
+#include <linux/bits.h>
+#include <linux/pm.h>
+#include <linux/types.h>
+
+#define	LOONGSON_SPI_SPCR_REG	0x00
+#define	LOONGSON_SPI_SPSR_REG	0x01
+#define	LOONGSON_SPI_FIFO_REG	0x02
+#define	LOONGSON_SPI_SPER_REG	0x03
+#define	LOONGSON_SPI_PARA_REG	0x04
+#define	LOONGSON_SPI_SFCS_REG	0x05
+#define	LOONGSON_SPI_TIMI_REG	0x06
+
+/* Bits definition for Loongson SPI register */
+#define	LOONGSON_SPI_PARA_MEM_EN	BIT(0)
+#define	LOONGSON_SPI_SPCR_CPHA	BIT(2)
+#define	LOONGSON_SPI_SPCR_CPOL	BIT(3)
+#define	LOONGSON_SPI_SPCR_SPE	BIT(6)
+#define	LOONGSON_SPI_SPSR_RFEMPTY	BIT(0)
+#define	LOONGSON_SPI_SPSR_WCOL	BIT(6)
+#define	LOONGSON_SPI_SPSR_SPIF	BIT(7)
+
+struct device;
+struct spi_controller;
+
+struct loongson_spi {
+	struct	spi_controller	*controller;
+	void __iomem		*base;
+	int			cs_active;
+	unsigned int		hz;
+	unsigned char		spcr;
+	unsigned char		sper;
+	unsigned char		spsr;
+	unsigned char		para;
+	unsigned char		sfcs;
+	unsigned char		timi;
+	unsigned int		mode;
+	u64			clk_rate;
+};
+
+int loongson_spi_init_controller(struct device *dev, void __iomem *reg);
+extern const struct dev_pm_ops loongson_spi_dev_pm_ops;
+#endif /* __LINUX_SPI_LOONGSON_H */