spi: hisi-kunpeng: Add debugfs support

This patch uses debugfs_regset32 interface to create the registers dump
file. Use it instead of creating a generic debugfs file with manually
written read callback function.

With these entries, users can check all the SPI controller registers
during run time.

Signed-off-by: Jay Fang <f.fangjian@huawei.com>
Link: https://lore.kernel.org/r/1622789718-13977-1-git-send-email-f.fangjian@huawei.com
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: Jay Fang

drivers/spi/spi-hisi-kunpeng.c

@@ -9,6 +9,7 @@
 
 #include <linux/acpi.h>
 #include <linux/bitfield.h>
+#include <linux/debugfs.h>
 #include <linux/delay.h>
 #include <linux/err.h>
 #include <linux/interrupt.h>
@@ -126,15 +127,57 @@ struct hisi_spi {
 	void __iomem		*regs;
 	int			irq;
 	u32			fifo_len; /* depth of the FIFO buffer */
+	u16			bus_num;
 
 	/* Current message transfer state info */
 	const void		*tx;
 	unsigned int		tx_len;
 	void			*rx;
 	unsigned int		rx_len;
 	u8			n_bytes; /* current is a 1/2/4 bytes op */
+
+	struct dentry *debugfs;
+	struct debugfs_regset32 regset;
+};
+
+#define HISI_SPI_DBGFS_REG(_name, _off)	\
+{					\
+	.name = _name,			\
+	.offset = _off,			\
+}
+
+static const struct debugfs_reg32 hisi_spi_regs[] = {
+	HISI_SPI_DBGFS_REG("CSCR", HISI_SPI_CSCR),
+	HISI_SPI_DBGFS_REG("CR", HISI_SPI_CR),
+	HISI_SPI_DBGFS_REG("ENR", HISI_SPI_ENR),
+	HISI_SPI_DBGFS_REG("FIFOC", HISI_SPI_FIFOC),
+	HISI_SPI_DBGFS_REG("IMR", HISI_SPI_IMR),
+	HISI_SPI_DBGFS_REG("DIN", HISI_SPI_DIN),
+	HISI_SPI_DBGFS_REG("DOUT", HISI_SPI_DOUT),
+	HISI_SPI_DBGFS_REG("SR", HISI_SPI_SR),
+	HISI_SPI_DBGFS_REG("RISR", HISI_SPI_RISR),
+	HISI_SPI_DBGFS_REG("ISR", HISI_SPI_ISR),
+	HISI_SPI_DBGFS_REG("ICR", HISI_SPI_ICR),
+	HISI_SPI_DBGFS_REG("VERSION", HISI_SPI_VERSION),
 };
 
+static int hisi_spi_debugfs_init(struct hisi_spi *hs)
+{
+	char name[32];
+
+	snprintf(name, 32, "hisi_spi%d", hs->bus_num);
+	hs->debugfs = debugfs_create_dir(name, NULL);
+	if (!hs->debugfs)
+		return -ENOMEM;
+
+	hs->regset.regs = hisi_spi_regs;
+	hs->regset.nregs = ARRAY_SIZE(hisi_spi_regs);
+	hs->regset.base = hs->regs;
+	debugfs_create_regset32("registers", 0400, hs->debugfs, &hs->regset);
+
+	return 0;
+}
+
 static u32 hisi_spi_busy(struct hisi_spi *hs)
 {
 	return readl(hs->regs + HISI_SPI_SR) & SR_BUSY;
@@ -424,6 +467,7 @@ static int hisi_spi_probe(struct platform_device *pdev)
 	hs = spi_controller_get_devdata(master);
 	hs->dev = dev;
 	hs->irq = irq;
+	hs->bus_num = pdev->id;
 
 	hs->regs = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(hs->regs))
@@ -446,7 +490,7 @@ static int hisi_spi_probe(struct platform_device *pdev)
 	master->use_gpio_descriptors = true;
 	master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH | SPI_LOOP;
 	master->bits_per_word_mask = SPI_BPW_RANGE_MASK(4, 32);
-	master->bus_num = pdev->id;
+	master->bus_num = hs->bus_num;
 	master->setup = hisi_spi_setup;
 	master->cleanup = hisi_spi_cleanup;
 	master->transfer_one = hisi_spi_transfer_one;
@@ -462,6 +506,9 @@ static int hisi_spi_probe(struct platform_device *pdev)
 		return ret;
 	}
 
+	if (hisi_spi_debugfs_init(hs))
+		dev_info(dev, "failed to create debugfs dir\n");
+
 	ret = spi_register_controller(master);
 	if (ret) {
 		dev_err(dev, "failed to register spi master, ret=%d\n", ret);
@@ -478,7 +525,9 @@ static int hisi_spi_probe(struct platform_device *pdev)
 static int hisi_spi_remove(struct platform_device *pdev)
 {
 	struct spi_controller *master = platform_get_drvdata(pdev);
+	struct hisi_spi *hs = spi_controller_get_devdata(master);
 
+	debugfs_remove_recursive(hs->debugfs);
 	spi_unregister_controller(master);
 
 	return 0;