spi: nuvoton: add NPCM PSPI controller driver

Add Nuvoton NPCM BMC Peripheral SPI controller driver.
NPCM750 include two general-purpose SPI interface.

Signed-off-by: Jim Liu <JJLIU0@nuvoton.com>
Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>

drivers/spi/Kconfig

@@ -321,6 +321,11 @@ config NPCM_FIU_SPI
 	  This enables support for the Flash Interface Unit SPI controller
 	  in master mode.
 
+config NPCM_PSPI
+	bool "PSPI driver for Nuvoton NPCM SoC"
+	help
+	  PSPI driver for NPCM SoC
+
 config NXP_FSPI
 	bool "NXP FlexSPI driver"
 	depends on SPI_MEM

drivers/spi/Makefile

@@ -52,6 +52,7 @@ obj-$(CONFIG_MVEBU_A3700_SPI) += mvebu_a3700_spi.o
 obj-$(CONFIG_MXC_SPI) += mxc_spi.o
 obj-$(CONFIG_MXS_SPI) += mxs_spi.o
 obj-$(CONFIG_NPCM_FIU_SPI) += npcm_fiu_spi.o
+obj-$(CONFIG_NPCM_PSPI) += npcm_pspi.o
 obj-$(CONFIG_NXP_FSPI) += nxp_fspi.o
 obj-$(CONFIG_ATCSPI200_SPI) += atcspi200_spi.o
 obj-$(CONFIG_OCTEON_SPI) += octeon_spi.o

drivers/spi/npcm_pspi.c

@@ -0,0 +1,226 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (c) 2021 Nuvoton Technology.
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <spi.h>
+#include <clk.h>
+#include <asm/gpio.h>
+#include <linux/iopoll.h>
+
+#define MAX_DIV	127
+
+/* Register offsets */
+#define PSPI_DATA		0
+#define PSPI_CTL1		2
+#define PSPI_STAT		4
+
+/* PSPI_CTL1 fields */
+#define PSPI_CTL1_SPIEN		BIT(0)
+#define PSPI_CTL1_SCM		BIT(7)
+#define PSPI_CTL1_SCIDL		BIT(8)
+#define PSPI_CTL1_SCDV_MASK	GENMASK(15, 9)
+#define PSPI_CTL1_SCDV_SHIFT	9
+
+/* PSPI_STAT fields */
+#define PSPI_STAT_BSY		BIT(0)
+#define PSPI_STAT_RBF		BIT(1)
+
+struct npcm_pspi_priv {
+	void __iomem *base;
+	struct clk clk;
+	struct gpio_desc cs_gpio;
+	u32 max_hz;
+};
+
+static inline void spi_cs_activate(struct udevice *dev)
+{
+	struct udevice *bus = dev->parent;
+	struct npcm_pspi_priv *priv = dev_get_priv(bus);
+
+	dm_gpio_set_value(&priv->cs_gpio, 0);
+}
+
+static inline void spi_cs_deactivate(struct udevice *dev)
+{
+	struct udevice *bus = dev->parent;
+	struct npcm_pspi_priv *priv = dev_get_priv(bus);
+
+	dm_gpio_set_value(&priv->cs_gpio, 1);
+}
+
+static inline void npcm_pspi_enable(struct npcm_pspi_priv *priv)
+{
+	u16 val;
+
+	val = readw(priv->base + PSPI_CTL1);
+	val |= PSPI_CTL1_SPIEN;
+	writew(val, priv->base + PSPI_CTL1);
+}
+
+static inline void npcm_pspi_disable(struct npcm_pspi_priv *priv)
+{
+	u16 val;
+
+	val = readw(priv->base + PSPI_CTL1);
+	val &= ~PSPI_CTL1_SPIEN;
+	writew(val, priv->base + PSPI_CTL1);
+}
+
+static int npcm_pspi_xfer(struct udevice *dev, unsigned int bitlen,
+			  const void *dout, void *din, unsigned long flags)
+{
+	struct udevice *bus = dev->parent;
+	struct npcm_pspi_priv *priv = dev_get_priv(bus);
+	void __iomem *base = priv->base;
+	const u8 *tx = dout;
+	u8 *rx = din;
+	u32 bytes = bitlen / 8;
+	u8 tmp;
+	u32 val;
+	int i, ret = 0;
+
+	npcm_pspi_enable(priv);
+
+	if (flags & SPI_XFER_BEGIN)
+		spi_cs_activate(dev);
+
+	for (i = 0; i < bytes; i++) {
+		/* Making sure we can write */
+		ret = readb_poll_timeout(base + PSPI_STAT, val,
+					 !(val & PSPI_STAT_BSY),
+					 1000000);
+		if (ret < 0)
+			break;
+
+		if (tx)
+			writeb(*tx++, base + PSPI_DATA);
+		else
+			writeb(0, base + PSPI_DATA);
+
+		/* Wait till write completed */
+		ret = readb_poll_timeout(base + PSPI_STAT, val,
+					 !(val & PSPI_STAT_BSY),
+					 1000000);
+		if (ret < 0)
+			break;
+
+		/* Wait till read buffer full */
+		ret = readb_poll_timeout(base + PSPI_STAT, val,
+					 (val & PSPI_STAT_RBF),
+					 1000000);
+		if (ret < 0)
+			break;
+
+		tmp = readb(base + PSPI_DATA);
+		if (rx)
+			*rx++ = tmp;
+	}
+
+	if (flags & SPI_XFER_END)
+		spi_cs_deactivate(dev);
+
+	npcm_pspi_disable(priv);
+
+	return ret;
+}
+
+static int npcm_pspi_set_speed(struct udevice *bus, uint speed)
+{
+	struct npcm_pspi_priv *priv = dev_get_priv(bus);
+	ulong apb_clock;
+	u32 divisor;
+	u16 val;
+
+	apb_clock = clk_get_rate(&priv->clk);
+	if (!apb_clock)
+		return -EINVAL;
+
+	if (speed > priv->max_hz)
+		speed = priv->max_hz;
+
+	divisor = DIV_ROUND_CLOSEST(apb_clock, (2 * speed) - 1);
+	if (divisor > MAX_DIV)
+		divisor = MAX_DIV;
+
+	val = readw(priv->base + PSPI_CTL1);
+	val &= ~PSPI_CTL1_SCDV_MASK;
+	val |= divisor << PSPI_CTL1_SCDV_SHIFT;
+	writew(val, priv->base + PSPI_CTL1);
+
+	debug("%s: apb_clock=%lu speed=%d divisor=%u\n",
+	      __func__, apb_clock, speed, divisor);
+
+	return 0;
+}
+
+static int npcm_pspi_set_mode(struct udevice *bus, uint mode)
+{
+	struct npcm_pspi_priv *priv = dev_get_priv(bus);
+	u16 pspi_mode, val;
+
+	switch (mode & (SPI_CPOL | SPI_CPHA)) {
+	case SPI_MODE_0:
+		pspi_mode = 0;
+		break;
+	case SPI_MODE_1:
+		pspi_mode = PSPI_CTL1_SCM;
+		break;
+	case SPI_MODE_2:
+		pspi_mode = PSPI_CTL1_SCIDL;
+		break;
+	case SPI_MODE_3:
+		pspi_mode = PSPI_CTL1_SCIDL | PSPI_CTL1_SCM;
+		break;
+	default:
+		break;
+	}
+
+	val = readw(priv->base + PSPI_CTL1);
+	val &= ~(PSPI_CTL1_SCIDL | PSPI_CTL1_SCM);
+	val |= pspi_mode;
+	writew(val, priv->base + PSPI_CTL1);
+
+	return 0;
+}
+
+static int npcm_pspi_probe(struct udevice *bus)
+{
+	struct npcm_pspi_priv *priv = dev_get_priv(bus);
+	int node = dev_of_offset(bus);
+	int ret;
+
+	ret = clk_get_by_index(bus, 0, &priv->clk);
+	if (ret < 0)
+		return ret;
+
+	priv->base = dev_read_addr_ptr(bus);
+	priv->max_hz = dev_read_u32_default(bus, "spi-max-frequency", 0);
+	gpio_request_by_name_nodev(offset_to_ofnode(node), "cs-gpios", 0,
+				   &priv->cs_gpio, GPIOD_IS_OUT);
+
+	return 0;
+}
+
+static const struct dm_spi_ops npcm_pspi_ops = {
+	.xfer           = npcm_pspi_xfer,
+	.set_speed      = npcm_pspi_set_speed,
+	.set_mode       = npcm_pspi_set_mode,
+};
+
+static const struct udevice_id npcm_pspi_ids[] = {
+	{ .compatible = "nuvoton,npcm845-pspi"},
+	{ .compatible = "nuvoton,npcm750-pspi"},
+	{ }
+};
+
+U_BOOT_DRIVER(npcm_pspi) = {
+	.name   = "npcm_pspi",
+	.id     = UCLASS_SPI,
+	.of_match = npcm_pspi_ids,
+	.ops    = &npcm_pspi_ops,
+	.priv_auto = sizeof(struct npcm_pspi_priv),
+	.probe  = npcm_pspi_probe,
+};