Date:   Wed,  8 Mar 2023 10:59:08 +0800
From:   Yinbo Zhu <zhuyinbo@...ngson.cn>
To:     Mark Brown <broonie@...nel.org>, Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        linux-spi@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     Jianmin Lv <lvjianmin@...ngson.cn>, wanghongliang@...ngson.cn,
        Liu Peibao <liupeibao@...ngson.cn>,
        loongson-kernel@...ts.loongnix.cn, Yinbo Zhu <zhuyinbo@...ngson.cn>
Subject: [PATCH v1 2/2] 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 to use DTS and PCI framework to
register spi device resources.

Signed-off-by: Yinbo Zhu <zhuyinbo@...ngson.cn>
---
 MAINTAINERS                |   1 +
 drivers/spi/Kconfig        |  10 +
 drivers/spi/Makefile       |   1 +
 drivers/spi/spi-loongson.c | 502 +++++++++++++++++++++++++++++++++++++
 4 files changed, 514 insertions(+)
 create mode 100644 drivers/spi/spi-loongson.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 0efb739e793f..2fd7a00ab120 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -12161,6 +12161,7 @@ M:	Yinbo Zhu <zhuyinbo@...ngson.cn>
 L:	linux-spi@...r.kernel.org
 S:	Maintained
 F:	Documentation/devicetree/bindings/spi/loongson,ls-spi.yaml
+F:	drivers/spi/spi-loongson.c
 
 LSILOGIC MPT FUSION DRIVERS (FC/SAS/SPI)
 M:	Sathya Prakash <sathya.prakash@...adcom.com>
diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index 36a18c215163..ad90b531ff96 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -509,6 +509,16 @@ config SPI_LM70_LLP
 	  which interfaces to an LM70 temperature sensor using
 	  a parallel port.
 
+config SPI_LOONGSON
+	tristate "Loongson SPI Controller Support"
+	depends on LOONGARCH && OF && PCI
+	help
+	  This bus driver supports the Loongson spi hardware controller in
+	  the Loongson platforms and supports to use DTS and 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_LP8841_RTC
 	tristate "ICP DAS LP-8841 SPI Controller for RTC"
 	depends on MACH_PXA27X_DT || COMPILE_TEST
diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
index d87cf75bee6a..cab3ff6d1814 100644
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -70,6 +70,7 @@ obj-$(CONFIG_SPI_INTEL_PLATFORM)	+= spi-intel-platform.o
 obj-$(CONFIG_SPI_LANTIQ_SSC)		+= spi-lantiq-ssc.o
 obj-$(CONFIG_SPI_JCORE)			+= spi-jcore.o
 obj-$(CONFIG_SPI_LM70_LLP)		+= spi-lm70llp.o
+obj-$(CONFIG_SPI_LOONGSON)		+= spi-loongson.o
 obj-$(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
diff --git a/drivers/spi/spi-loongson.c b/drivers/spi/spi-loongson.c
new file mode 100644
index 000000000000..26316e873965
--- /dev/null
+++ b/drivers/spi/spi-loongson.c
@@ -0,0 +1,502 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Loongson SPI Support
+ *
+ * Copyright (C) 2023 Loongson Technology Corporation Limited
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/interrupt.h>
+#include <linux/delay.h>
+#include <linux/platform_device.h>
+#include <linux/err.h>
+#include <linux/spi/spi.h>
+#include <linux/pci.h>
+#include <linux/clk.h>
+#include <linux/of.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_SPSR_SPIF	BIT(7)
+#define	LOONGSON_SPI_SPSR_WCOL	BIT(6)
+#define	LOONGSON_SPI_SPCR_SPE	BIT(6)
+
+struct loongson_spi {
+	struct work_struct	work;
+	spinlock_t		lock;
+	struct	list_head	msg_queue;
+	struct	spi_master	*master;
+	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;
+	struct workqueue_struct	*wq;
+	unsigned int		mode;
+	u64			clk_rate;
+};
+
+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 inline int loongson_spi_set_cs(struct loongson_spi *loongson_spi,
+				      struct spi_device *spi, int val)
+{
+	int cs;
+
+	if (spi->mode & SPI_CS_HIGH)
+		val = !val;
+
+	if (loongson_spi->mode & SPI_NO_CS)
+		loongson_spi_write_reg(loongson_spi, LOONGSON_SPI_SFCS_REG, 0);
+	else {
+		cs = loongson_spi_read_reg(loongson_spi, LOONGSON_SPI_SFCS_REG)
+					   & ~(0x11 << spi->chip_select);
+		loongson_spi_write_reg(loongson_spi,
+				       LOONGSON_SPI_SFCS_REG,
+				       (val ? (0x11 << spi->chip_select) :
+				       (0x1 << spi->chip_select)) | cs);
+	}
+
+	return 0;
+}
+
+static int loongson_spi_update_state(struct loongson_spi *loongson_spi,
+				     struct spi_device *spi, struct spi_transfer *t)
+{
+	unsigned int hz;
+	unsigned int div, div_tmp;
+	unsigned int bit;
+	unsigned char val;
+	const char rdiv[12] = {0, 1, 4, 2, 3, 5, 6, 7, 8, 9, 10, 11};
+
+	hz  = t ? t->speed_hz : spi->max_speed_hz;
+
+	if (!hz)
+		hz = spi->max_speed_hz;
+
+	if ((hz && loongson_spi->hz != hz) ||
+	    ((spi->mode ^ loongson_spi->mode) & (SPI_CPOL | SPI_CPHA))) {
+		div = DIV_ROUND_UP(loongson_spi->clk_rate, hz);
+		if (div < 2)
+			div = 2;
+		if (div > 4096)
+			div = 4096;
+
+		bit = fls(div) - 1;
+		if ((1<<bit) == div)
+			bit--;
+		div_tmp = rdiv[bit];
+		dev_dbg(&spi->dev, "clk_rate = %llu hz = %d div_tmp = %d bit = %d\n",
+			loongson_spi->clk_rate, hz, div_tmp, bit);
+
+		loongson_spi->hz = hz;
+		loongson_spi->spcr = div_tmp & 3;
+		loongson_spi->sper = (div_tmp >> 2) & 3;
+		val = loongson_spi_read_reg(loongson_spi, LOONGSON_SPI_SPCR_REG);
+		val &= ~0xc;
+		if (spi->mode & SPI_CPOL)
+			val |= 8;
+		if (spi->mode & SPI_CPHA)
+			val |= 4;
+
+		loongson_spi_write_reg(loongson_spi, LOONGSON_SPI_SPCR_REG, (val & ~3) |
+				       loongson_spi->spcr);
+		val = loongson_spi_read_reg(loongson_spi, LOONGSON_SPI_SPER_REG);
+		loongson_spi_write_reg(loongson_spi, LOONGSON_SPI_SPER_REG, (val & ~3) |
+				       loongson_spi->sper);
+		loongson_spi->mode &= SPI_NO_CS;
+		loongson_spi->mode |= spi->mode;
+	}
+
+	return 0;
+}
+
+static int loongson_spi_setup(struct spi_device *spi)
+{
+	struct loongson_spi *loongson_spi;
+
+	loongson_spi = spi_master_get_devdata(spi->master);
+	if (spi->bits_per_word % 8)
+		return -EINVAL;
+
+	if (spi->chip_select >= spi->master->num_chipselect)
+		return -EINVAL;
+
+	loongson_spi_update_state(loongson_spi, spi, NULL);
+	loongson_spi_set_cs(loongson_spi, spi, 1);
+
+	return 0;
+}
+
+static int loongson_spi_write_read_8bit(struct spi_device *spi, const u8 **tx_buf,
+					u8 **rx_buf, unsigned int num)
+{
+	struct loongson_spi *loongson_spi = spi_master_get_devdata(spi->master);
+
+	if (tx_buf && *tx_buf) {
+		loongson_spi_write_reg(loongson_spi, LOONGSON_SPI_FIFO_REG, *((*tx_buf)++));
+		while ((loongson_spi_read_reg(loongson_spi, LOONGSON_SPI_SPSR_REG) & 0x1) == 1)
+			;
+	} else {
+		loongson_spi_write_reg(loongson_spi, LOONGSON_SPI_FIFO_REG, 0);
+		while ((loongson_spi_read_reg(loongson_spi, LOONGSON_SPI_SPSR_REG) & 0x1) == 1)
+			;
+	}
+
+	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 0;
+}
+
+static unsigned int loongson_spi_write_read(struct spi_device *spi, struct spi_transfer *xfer)
+{
+	unsigned int count;
+	const u8 *tx = xfer->tx_buf;
+	u8 *rx = xfer->rx_buf;
+
+	count = xfer->len;
+
+	do {
+		if (loongson_spi_write_read_8bit(spi, &tx, &rx, count) < 0)
+			goto out;
+		count--;
+	} while (count);
+
+out:
+	return xfer->len - count;
+}
+
+static void loongson_spi_work(struct work_struct *work)
+{
+	int param;
+	struct spi_message *m;
+	struct spi_device  *spi;
+	struct spi_transfer *t = NULL;
+	struct loongson_spi *loongson_spi = container_of(work, struct loongson_spi, work);
+
+	spin_lock(&loongson_spi->lock);
+	param = loongson_spi_read_reg(loongson_spi, LOONGSON_SPI_PARA_REG);
+	loongson_spi_write_reg(loongson_spi, LOONGSON_SPI_PARA_REG, param&~1);
+	while (!list_empty(&loongson_spi->msg_queue)) {
+		m = container_of(loongson_spi->msg_queue.next, struct spi_message, queue);
+
+		list_del_init(&m->queue);
+		spin_unlock(&loongson_spi->lock);
+		spi = m->spi;
+		loongson_spi_set_cs(loongson_spi, spi, 0);
+
+		list_for_each_entry(t, &m->transfers, transfer_list) {
+			loongson_spi_update_state(loongson_spi, spi, t);
+			if (t->len)
+				m->actual_length += loongson_spi_write_read(spi, t);
+		}
+
+		loongson_spi_set_cs(loongson_spi, spi, 1);
+		m->complete(m->context);
+		spin_lock(&loongson_spi->lock);
+	}
+
+	loongson_spi_write_reg(loongson_spi, LOONGSON_SPI_PARA_REG, param);
+	spin_unlock(&loongson_spi->lock);
+}
+
+static int loongson_spi_transfer(struct spi_device *spi, struct spi_message *m)
+{
+	struct loongson_spi *loongson_spi;
+	struct spi_transfer *t = NULL;
+
+	m->status = 0;
+	m->actual_length = 0;
+
+	if (list_empty(&m->transfers) || !m->complete)
+		return -EINVAL;
+
+	loongson_spi = spi_master_get_devdata(spi->master);
+
+	list_for_each_entry(t, &m->transfers, transfer_list) {
+
+		if (t->tx_buf == NULL && t->rx_buf == NULL && t->len) {
+			dev_err(&spi->dev, "invalid transfer data buffers\n");
+			goto msg_rejected;
+		}
+	}
+
+	spin_lock(&loongson_spi->lock);
+	list_add_tail(&m->queue, &loongson_spi->msg_queue);
+	queue_work(loongson_spi->wq, &loongson_spi->work);
+	spin_unlock(&loongson_spi->lock);
+
+	return 0;
+msg_rejected:
+	m->status = -EINVAL;
+
+	if (m->complete)
+		m->complete(m->context);
+
+	return -EINVAL;
+}
+
+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);
+}
+
+static int loongson_spi_init_master(struct device *dev, struct resource *res)
+{
+	struct spi_master *master;
+	struct loongson_spi *spi;
+	struct clk *clk;
+	int ret;
+
+	master = spi_alloc_master(dev, sizeof(struct loongson_spi));
+	if (master == NULL) {
+		dev_dbg(dev, "master allocation failed\n");
+		return -ENOMEM;
+	}
+
+	master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH;
+	master->setup = loongson_spi_setup;
+	master->transfer = loongson_spi_transfer;
+	master->num_chipselect = 4;
+	master->dev.of_node = of_node_get(dev->of_node);
+	dev_set_drvdata(dev, master);
+
+	spi = spi_master_get_devdata(master);
+
+	spi->master = master;
+
+	spi->wq	= create_singlethread_workqueue("loongson-spi");
+
+	spi->base = devm_ioremap(dev, res->start, resource_size(res));
+	if (spi->base == NULL) {
+		dev_err(dev, "cannot map io\n");
+		ret = -ENXIO;
+		goto free_master;
+	}
+
+	clk = devm_clk_get(dev, NULL);
+	if (!IS_ERR(clk))
+		spi->clk_rate = clk_get_rate(clk);
+
+	loongson_spi_reginit(spi);
+
+	spi->mode = 0;
+	if (of_get_property(dev->of_node, "spi-nocs", NULL))
+		spi->mode |= SPI_NO_CS;
+
+	INIT_WORK(&spi->work, loongson_spi_work);
+
+	spin_lock_init(&spi->lock);
+	INIT_LIST_HEAD(&spi->msg_queue);
+
+	ret = spi_register_master(master);
+	if (ret < 0)
+		goto free_master;
+
+	return ret;
+
+free_master:
+	kfree(master);
+	spi_master_put(master);
+
+	return ret;
+}
+
+static int loongson_spi_platform_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct resource *res;
+	int ret;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (res == NULL) {
+		dev_err(dev, "cannot get io resource memory\n");
+		return -ENOENT;
+	}
+
+	ret = loongson_spi_init_master(dev, res);
+	if (ret)
+		dev_err(dev, "failed to initialize master\n");
+
+	return ret;
+}
+
+static int __maybe_unused loongson_spi_suspend(struct device *dev)
+{
+	struct loongson_spi *loongson_spi;
+	struct spi_master *master;
+
+	master = dev_get_drvdata(dev);
+	loongson_spi = spi_master_get_devdata(master);
+
+	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_master *master;
+
+	master = dev_get_drvdata(dev);
+	loongson_spi = spi_master_get_devdata(master);
+
+	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);
+
+	return 0;
+}
+
+static const struct dev_pm_ops loongson_spi_dev_pm_ops = {
+	.suspend = loongson_spi_suspend,
+	.resume = loongson_spi_resume,
+};
+
+static const struct of_device_id loongson_spi_id_table[] = {
+	{ .compatible = "loongson,ls2k-spi", },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, loongson_spi_id_table);
+
+static struct platform_driver loongson_spi_driver = {
+	.probe = loongson_spi_platform_probe,
+	.driver	= {
+		.name	= "loongson-spi",
+		.owner	= THIS_MODULE,
+		.bus = &platform_bus_type,
+		.pm = &loongson_spi_dev_pm_ops,
+		.of_match_table = loongson_spi_id_table,
+	},
+};
+
+static int loongson_spi_pci_register(struct pci_dev *pdev,
+			const struct pci_device_id *ent)
+{
+	int ret;
+	unsigned char v8;
+	struct resource res[2];
+	struct device *dev = &pdev->dev;
+
+	ret = pci_enable_device(pdev);
+	if (ret < 0) {
+		dev_err(dev, "cannot enable pci device\n");
+		goto err_out;
+	}
+
+	ret = pci_request_region(pdev, 0, "loongson-spi io");
+	if (ret < 0) {
+		dev_err(dev, "cannot request region 0.\n");
+		goto err_out;
+	}
+
+	res[0].start = pci_resource_start(pdev, 0);
+	res[0].end = pci_resource_end(pdev, 0);
+	ret = pci_read_config_byte(pdev, PCI_INTERRUPT_LINE, &v8);
+
+	if (ret == PCIBIOS_SUCCESSFUL) {
+		res[1].start = v8;
+		res[1].end = v8;
+	}
+
+	ret = loongson_spi_init_master(dev, res);
+	if (ret)
+		dev_err(dev, "failed to initialize master\n");
+
+err_out:
+	return ret;
+}
+
+static void loongson_spi_pci_unregister(struct pci_dev *pdev)
+{
+	pci_release_region(pdev, 0);
+}
+
+static struct pci_device_id loongson_spi_devices[] = {
+	{PCI_DEVICE(0x14, 0x7a0b)},
+	{PCI_DEVICE(0x14, 0x7a1b)},
+	{0, 0, 0, 0, 0, 0, 0}
+};
+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,
+	.remove     = loongson_spi_pci_unregister,
+};
+
+static int __init loongson_spi_init(void)
+{
+	int ret;
+
+	ret =  platform_driver_register(&loongson_spi_driver);
+	if (ret)
+		return ret;
+
+	ret = pci_register_driver(&loongson_spi_pci_driver);
+	if (ret) {
+		platform_driver_unregister(&loongson_spi_driver);
+		return ret;
+	}
+
+	return 0;
+}
+
+static void __exit loongson_spi_exit(void)
+{
+	platform_driver_unregister(&loongson_spi_driver);
+	pci_unregister_driver(&loongson_spi_pci_driver);
+}
+
+subsys_initcall(loongson_spi_init);
+module_exit(loongson_spi_exit);
+
+MODULE_DESCRIPTION("Loongson spi driver");
+MODULE_LICENSE("GPL");
-- 
2.20.1

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