[PATCH v2 10/12] spi: add driver for J-Core SPI controller

[Rich Felker <dalias@libc.org>]

Signed-off-by: Rich Felker <dalias@libc.org>
---
My previous post of the patch series accidentally omitted omitted
Cc'ing of subsystem maintainers for the necessary clocksource,
irqchip, and spi drivers. Please ack if this looks ok because I want
to get it merged as part of the arch/sh pull request for 4.7.

 drivers/spi/Kconfig     |   4 +
 drivers/spi/Makefile    |   1 +
 drivers/spi/spi-jcore.c | 266 ++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 271 insertions(+)
 create mode 100644 drivers/spi/spi-jcore.c

diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index 9d8c84b..5bd2ccf 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -285,6 +285,10 @@ config SPI_IMX
 	  This enables using the Freescale i.MX SPI controllers in master
 	  mode.
 
+config SPI_JCORE
+	tristate "J-Core SPI Master"
+	depends on OF
+
 config SPI_LM70_LLP
 	tristate "Parallel port adapter for LM70 eval board (DEVELOPMENT)"
 	depends on PARPORT
diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
index fbb255c..6a34124 100644
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -46,6 +46,7 @@ obj-$(CONFIG_SPI_FSL_SPI)		+= spi-fsl-spi.o
 obj-$(CONFIG_SPI_GPIO)			+= spi-gpio.o
 obj-$(CONFIG_SPI_IMG_SPFI)		+= spi-img-spfi.o
 obj-$(CONFIG_SPI_IMX)			+= spi-imx.o
+obj-$(CONFIG_SPI_JCORE)			+= spi-jcore.o
 obj-$(CONFIG_SPI_LM70_LLP)		+= spi-lm70llp.o
 obj-$(CONFIG_SPI_LP8841_RTC)		+= spi-lp8841-rtc.o
 obj-$(CONFIG_SPI_MESON_SPIFC)		+= spi-meson-spifc.o
diff --git a/drivers/spi/spi-jcore.c b/drivers/spi/spi-jcore.c
new file mode 100644
index 0000000..552304c
--- /dev/null
+++ b/drivers/spi/spi-jcore.c
@@ -0,0 +1,266 @@
+/*
+ * J-Core SPI controller driver
+ *
+ * Copyright (C) 2012-2016 SEI Inc.
+ *
+ * Current version by Rich Felker
+ * Based loosely on initial version by Oleksandr G Zhadan
+ *
+ */
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/errno.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/spi/spi.h>
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/delay.h>
+
+#define USE_MESSAGE_MODE 1
+
+#define DRV_NAME "jcore_spi"
+
+#define MAX_SPI_SPEED			12500000	/* 12.5 MHz */
+
+#define CTRL_REG		0x0
+#define DATA_REG		0x4
+
+#define SPI_NOCHIP_CS	0
+#define SPI_FLASH_CS	1
+#define SPI_CONF_CS	2
+#define SPI_SD_CS	2
+#define SPI_CODEC_CS	3
+
+#define JCORE_SPI_CTRL_ACS		0x01
+#define JCORE_SPI_CTRL_XMIT		0x02
+#define JCORE_SPI_STAT_BUSY		0x02
+#define JCORE_SPI_CTRL_CCS		0x04
+#define JCORE_SPI_CTRL_LOOP		0x08
+#define JCORE_SPI_CTRL_DCS		0x10
+
+#define JCORE_SPI_WAIT_RDY_MAX_LOOP	2000000	/* in usec */
+
+struct jcore_spi {
+	struct spi_master *master;
+	void __iomem *base;
+	volatile unsigned int ctrlReg;
+	unsigned int csReg;
+	unsigned int speedReg;
+	unsigned int speed_hz;
+};
+
+static void jcore_spi_wait_till_ready(struct jcore_spi *hw, int timeout)
+{
+	while (timeout--) {
+		hw->ctrlReg = readl(hw->base + CTRL_REG);
+		if (!(hw->ctrlReg & JCORE_SPI_STAT_BUSY))
+			return;
+		cpu_relax();
+	}
+	pr_err("%s: Timeout..\n", __func__);
+}
+
+static void jcore_spi_program(struct jcore_spi *hw)
+{
+	jcore_spi_wait_till_ready(hw, JCORE_SPI_WAIT_RDY_MAX_LOOP);
+	writel(hw->csReg | hw->speedReg, hw->base + CTRL_REG);	
+}
+
+static void jcore_spi_chipsel(struct spi_device *spi, bool value)
+{
+	struct jcore_spi *hw = spi_master_get_devdata(spi->master);
+
+	pr_debug("%s: CS=%d\n", __func__, value);
+
+	hw->csReg = ( JCORE_SPI_CTRL_ACS | JCORE_SPI_CTRL_CCS | JCORE_SPI_CTRL_DCS )
+		^ (!value << 2*spi->chip_select);
+
+	jcore_spi_program(hw);
+}
+
+static void jcore_spi_baudrate(struct jcore_spi *hw, int speed)
+{
+	if (speed == hw->speed_hz) return;
+	hw->speed_hz = speed;
+	hw->speedReg = ((MAX_SPI_SPEED / speed) - 1) << 27;
+	jcore_spi_program(hw);
+	pr_debug("%s: speed=%d pre=0x%x\n", __func__, speed, hw->speedReg);
+}
+
+static int jcore_spi_txrx(struct spi_master *master, struct spi_device *spi, struct spi_transfer *t)
+{
+	struct jcore_spi *hw = spi_master_get_devdata(master);
+
+	void *ctrl_reg = hw->base + CTRL_REG;
+	void *data_reg = hw->base + DATA_REG;
+	int timeout;
+	int xmit;
+	int status;
+
+	/* data buffers */
+	const unsigned char *tx;
+	unsigned char *rx;
+	int len;
+	int count;
+
+	jcore_spi_baudrate(hw, t->speed_hz);
+
+	xmit = hw->csReg | hw->speedReg | JCORE_SPI_CTRL_XMIT;
+	tx = t->tx_buf;
+	rx = t->rx_buf;
+	len = t->len;
+
+	for (count = 0; count < len; count++) {
+		timeout = JCORE_SPI_WAIT_RDY_MAX_LOOP;
+		do status = readl(ctrl_reg);
+		while ((status & JCORE_SPI_STAT_BUSY) && --timeout);
+		if (!timeout) break;
+
+		writel(tx ? *tx++ : 0, data_reg);
+		writel(xmit, ctrl_reg);
+
+		timeout = JCORE_SPI_WAIT_RDY_MAX_LOOP;
+		do status = readl(ctrl_reg);
+		while ((status & JCORE_SPI_STAT_BUSY) && --timeout);
+		if (!timeout) break;
+
+		if (rx) *rx++ = readl(data_reg);
+	}
+
+#if !USE_MESSAGE_MODE
+	spi_finalize_current_transfer(master);
+#endif
+
+	return count<len ? -EREMOTEIO : 0;
+}
+
+#if USE_MESSAGE_MODE
+static int jcore_spi_transfer_one_message(struct spi_master *master,
+					struct spi_message *msg)
+{
+	struct spi_device *spi = msg->spi;
+	struct spi_transfer *xfer;
+	bool keep_cs = false;
+	int ret = 0;
+
+	jcore_spi_chipsel(spi, false);
+
+	list_for_each_entry(xfer, &msg->transfers, transfer_list) {
+		ret = jcore_spi_txrx(master, spi, xfer);
+		if (ret) break;
+		if (xfer->delay_usecs)
+			udelay(xfer->delay_usecs);
+		if (xfer->cs_change) {
+			if (list_is_last(&xfer->transfer_list,
+					 &msg->transfers)) {
+				keep_cs = true;
+			} else {
+				jcore_spi_chipsel(spi, true);
+				udelay(10);
+				jcore_spi_chipsel(spi, false);
+			}
+		}
+		msg->actual_length += xfer->len;
+	}
+
+	if (!keep_cs)
+		jcore_spi_chipsel(spi, true);
+
+	msg->status = ret;
+
+	spi_finalize_current_message(master);
+
+	return ret;
+}
+#endif
+
+static int jcore_spi_probe(struct platform_device *pdev)
+{
+	struct device_node *node = pdev->dev.of_node;
+	struct jcore_spi *hw;
+	struct spi_master *master;
+	struct resource *res;
+	int err = -ENODEV;
+
+	master = spi_alloc_master(&pdev->dev, sizeof(struct jcore_spi));
+	if (!master)
+		return err;
+
+	/* setup the master state. */
+	master->num_chipselect = 3;
+	master->mode_bits = SPI_MODE_3;
+#if USE_MESSAGE_MODE
+	master->transfer_one_message = jcore_spi_transfer_one_message;
+#else
+	master->transfer_one = jcore_spi_txrx;
+#endif
+	master->set_cs = jcore_spi_chipsel;
+	master->dev.of_node = node;
+
+	hw = spi_master_get_devdata(master);
+	hw->master = master;
+	platform_set_drvdata(pdev, hw);
+
+	/* find and map our resources */
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res)
+		goto exit_busy;
+	if (!devm_request_mem_region
+	    (&pdev->dev, res->start, resource_size(res), pdev->name))
+		goto exit_busy;
+	hw->base =
+	    devm_ioremap_nocache(&pdev->dev, res->start, resource_size(res));
+	if (!hw->base)
+		goto exit_busy;
+
+	jcore_spi_baudrate(hw, 400000);
+
+	pdev->dev.dma_mask = 0;
+	/* register our spi controller */
+	err = spi_register_master(master);
+	if (err)
+		goto exit;
+	dev_info(&pdev->dev, "base %p, noirq\n", hw->base);
+
+	return 0;
+
+exit_busy:
+	err = -EBUSY;
+exit:
+	platform_set_drvdata(pdev, NULL);
+	spi_master_put(master);
+	return err;
+}
+
+static int jcore_spi_remove(struct platform_device *dev)
+{
+	struct jcore_spi *hw = platform_get_drvdata(dev);
+	struct spi_master *master = hw->master;
+
+	platform_set_drvdata(dev, NULL);
+	spi_master_put(master);
+	return 0;
+}
+
+static const struct of_device_id jcore_spi_of_match[] = {
+	{ .compatible = "jcore,spi2" },
+	{},
+};
+
+static struct platform_driver jcore_spi_driver = {
+	.probe = jcore_spi_probe,
+	.remove = jcore_spi_remove,
+	.driver = {
+		.name = DRV_NAME,
+		.owner = THIS_MODULE,
+		.pm = NULL,
+		.of_match_table = jcore_spi_of_match,
+	},
+};
+
+module_platform_driver(jcore_spi_driver);
+
+MODULE_DESCRIPTION("J-Core SPI driver");
+MODULE_AUTHOR("Rich Felker <dalias@libc.org>");
+MODULE_ALIAS("platform:" DRV_NAME);
-- 
2.8.1