From 97ffc04a7528abe1d84c069d99afb19704d50224 Mon Sep 17 00:00:00 2001
From: Phil Sutter <phil@nwl.cc>
Date: Tue, 13 May 2014 00:18:58 +0200
Subject: [PATCH] spi: add rb4xx SPI driver

---
 drivers/spi/Kconfig     |   6 +
 drivers/spi/Makefile    |   1 +
 drivers/spi/spi-rb4xx.c | 507 ++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 514 insertions(+)
 create mode 100644 drivers/spi/spi-rb4xx.c

diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index 581ee2a..721f3a7 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -381,6 +381,12 @@ config SPI_RSPI
 	help
 	  SPI driver for Renesas RSPI and QSPI blocks.
 
+config SPI_RB4XX
+	tristate "Mikrotik RB4XX SPI master"
+	depends on SPI_MASTER && ATH79_MACH_RB4XX
+	help
+	  SPI controller driver for the Mikrotik RB4xx series boards.
+
 config SPI_S3C24XX
 	tristate "Samsung S3C24XX series SPI"
 	depends on ARCH_S3C24XX
diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
index 95af48d..e738c7a 100644
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -59,6 +59,7 @@ spi-pxa2xx-platform-$(CONFIG_SPI_PXA2XX_PXADMA)	+= spi-pxa2xx-pxadma.o
 spi-pxa2xx-platform-$(CONFIG_SPI_PXA2XX_DMA)	+= spi-pxa2xx-dma.o
 obj-$(CONFIG_SPI_PXA2XX)		+= spi-pxa2xx-platform.o
 obj-$(CONFIG_SPI_PXA2XX_PCI)		+= spi-pxa2xx-pci.o
+obj-$(CONFIG_SPI_RB4XX)			+= spi-rb4xx.o
 obj-$(CONFIG_SPI_RSPI)			+= spi-rspi.o
 obj-$(CONFIG_SPI_S3C24XX)		+= spi-s3c24xx-hw.o
 spi-s3c24xx-hw-y			:= spi-s3c24xx.o
diff --git a/drivers/spi/spi-rb4xx.c b/drivers/spi/spi-rb4xx.c
new file mode 100644
index 0000000..56260ff
--- /dev/null
+++ b/drivers/spi/spi-rb4xx.c
@@ -0,0 +1,507 @@
+/*
+ * SPI controller driver for the Mikrotik RB4xx boards
+ *
+ * Copyright (C) 2010 Gabor Juhos <juhosg@openwrt.org>
+ *
+ * This file was based on the patches for Linux 2.6.27.39 published by
+ * MikroTik for their RouterBoard 4xx series devices.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/delay.h>
+#include <linux/spinlock.h>
+#include <linux/workqueue.h>
+#include <linux/platform_device.h>
+#include <linux/spi/spi.h>
+
+#include <asm/mach-ath79/ar71xx_regs.h>
+#include <asm/mach-ath79/ath79.h>
+
+#define DRV_NAME	"rb4xx-spi"
+#define DRV_DESC	"Mikrotik RB4xx SPI controller driver"
+#define DRV_VERSION	"0.1.0"
+
+#define SPI_CTRL_FASTEST	0x40
+#define SPI_FLASH_HZ		33333334
+#define SPI_CPLD_HZ		33333334
+
+#define CPLD_CMD_READ_FAST	0x0b
+
+#undef RB4XX_SPI_DEBUG
+
+struct rb4xx_spi {
+	void __iomem		*base;
+	struct spi_master	*master;
+
+	unsigned		spi_ctrl_flash;
+	unsigned		spi_ctrl_fread;
+
+	struct clk		*ahb_clk;
+	unsigned long		ahb_freq;
+
+	spinlock_t		lock;
+	struct list_head	queue;
+	int			busy:1;
+	int			cs_wait;
+};
+
+static unsigned spi_clk_low = AR71XX_SPI_IOC_CS1;
+
+#ifdef RB4XX_SPI_DEBUG
+static inline void do_spi_delay(void)
+{
+	ndelay(20000);
+}
+#else
+static inline void do_spi_delay(void) { }
+#endif
+
+static inline void do_spi_init(struct spi_device *spi)
+{
+	unsigned cs = AR71XX_SPI_IOC_CS0 | AR71XX_SPI_IOC_CS1;
+
+	if (!(spi->mode & SPI_CS_HIGH))
+		cs ^= (spi->chip_select == 2) ? AR71XX_SPI_IOC_CS1 :
+						AR71XX_SPI_IOC_CS0;
+
+	spi_clk_low = cs;
+}
+
+static inline void do_spi_finish(void __iomem *base)
+{
+	do_spi_delay();
+	__raw_writel(AR71XX_SPI_IOC_CS0 | AR71XX_SPI_IOC_CS1,
+		     base + AR71XX_SPI_REG_IOC);
+}
+
+static inline void do_spi_clk(void __iomem *base, int bit)
+{
+	unsigned bval = spi_clk_low | ((bit & 1) ? AR71XX_SPI_IOC_DO : 0);
+
+	do_spi_delay();
+	__raw_writel(bval, base + AR71XX_SPI_REG_IOC);
+	do_spi_delay();
+	__raw_writel(bval | AR71XX_SPI_IOC_CLK, base + AR71XX_SPI_REG_IOC);
+}
+
+static void do_spi_byte(void __iomem *base, unsigned char byte)
+{
+	do_spi_clk(base, byte >> 7);
+	do_spi_clk(base, byte >> 6);
+	do_spi_clk(base, byte >> 5);
+	do_spi_clk(base, byte >> 4);
+	do_spi_clk(base, byte >> 3);
+	do_spi_clk(base, byte >> 2);
+	do_spi_clk(base, byte >> 1);
+	do_spi_clk(base, byte);
+
+	pr_debug("spi_byte sent 0x%02x got 0x%02x\n",
+	       (unsigned)byte,
+	       (unsigned char)__raw_readl(base + AR71XX_SPI_REG_RDS));
+}
+
+static inline void do_spi_clk_fast(void __iomem *base, unsigned bit1,
+				   unsigned bit2)
+{
+	unsigned bval = (spi_clk_low |
+			 ((bit1 & 1) ? AR71XX_SPI_IOC_DO : 0) |
+			 ((bit2 & 1) ? AR71XX_SPI_IOC_CS2 : 0));
+	do_spi_delay();
+	__raw_writel(bval, base + AR71XX_SPI_REG_IOC);
+	do_spi_delay();
+	__raw_writel(bval | AR71XX_SPI_IOC_CLK, base + AR71XX_SPI_REG_IOC);
+}
+
+static void do_spi_byte_fast(void __iomem *base, unsigned char byte)
+{
+	do_spi_clk_fast(base, byte >> 7, byte >> 6);
+	do_spi_clk_fast(base, byte >> 5, byte >> 4);
+	do_spi_clk_fast(base, byte >> 3, byte >> 2);
+	do_spi_clk_fast(base, byte >> 1, byte >> 0);
+
+	pr_debug("spi_byte_fast sent 0x%02x got 0x%02x\n",
+	       (unsigned)byte,
+	       (unsigned char) __raw_readl(base + AR71XX_SPI_REG_RDS));
+}
+
+static int rb4xx_spi_txrx(void __iomem *base, struct spi_transfer *t)
+{
+	const unsigned char *rxv_ptr = NULL;
+	const unsigned char *tx_ptr = t->tx_buf;
+	unsigned char *rx_ptr = t->rx_buf;
+	unsigned i;
+
+	pr_debug("spi_txrx len %u tx %u rx %u\n",
+	       t->len,
+	       (t->tx_buf ? 1 : 0),
+	       (t->rx_buf ? 1 : 0));
+
+	if (t->verify) {
+		rxv_ptr = tx_ptr;
+		tx_ptr = NULL;
+	}
+
+	for (i = 0; i < t->len; ++i) {
+		unsigned char sdata = tx_ptr ? tx_ptr[i] : 0;
+
+		if (t->fast_write)
+			do_spi_byte_fast(base, sdata);
+		else
+			do_spi_byte(base, sdata);
+
+		if (rx_ptr) {
+			rx_ptr[i] = __raw_readl(base + AR71XX_SPI_REG_RDS) & 0xff;
+		} else if (rxv_ptr) {
+			unsigned char c = __raw_readl(base + AR71XX_SPI_REG_RDS);
+			if (rxv_ptr[i] != c)
+				return i;
+		}
+	}
+
+	return i;
+}
+
+static int rb4xx_spi_read_fast(struct rb4xx_spi *rbspi,
+			       struct spi_message *m)
+{
+	struct spi_transfer *t;
+	const unsigned char *tx_ptr;
+	unsigned addr;
+	void __iomem *base = rbspi->base;
+
+	/* check for exactly two transfers */
+	if (list_empty(&m->transfers) ||
+	    list_is_last(m->transfers.next, &m->transfers) ||
+	    !list_is_last(m->transfers.next->next, &m->transfers)) {
+		return -1;
+	}
+
+	/* first transfer contains command and address  */
+	t = list_entry(m->transfers.next,
+		       struct spi_transfer, transfer_list);
+
+	if (t->len != 5 || t->tx_buf == NULL)
+		return -1;
+
+	tx_ptr = t->tx_buf;
+	if (tx_ptr[0] != CPLD_CMD_READ_FAST)
+		return -1;
+
+	addr = tx_ptr[1];
+	addr = tx_ptr[2] | (addr << 8);
+	addr = tx_ptr[3] | (addr << 8);
+	addr += (unsigned) base;
+
+	m->actual_length += t->len;
+
+	/* second transfer contains data itself */
+	t = list_entry(m->transfers.next->next,
+		       struct spi_transfer, transfer_list);
+
+	if (t->tx_buf && !t->verify)
+		return -1;
+
+	__raw_writel(AR71XX_SPI_FS_GPIO, base + AR71XX_SPI_REG_FS);
+	__raw_writel(rbspi->spi_ctrl_fread, base + AR71XX_SPI_REG_CTRL);
+	__raw_writel(0, base + AR71XX_SPI_REG_FS);
+
+	if (t->rx_buf) {
+		memcpy(t->rx_buf, (const void *)addr, t->len);
+	} else if (t->tx_buf) {
+		unsigned char buf[t->len];
+		memcpy(buf, (const void *)addr, t->len);
+		if (memcmp(t->tx_buf, buf, t->len) != 0)
+			m->status = -EMSGSIZE;
+	}
+	m->actual_length += t->len;
+
+	if (rbspi->spi_ctrl_flash != rbspi->spi_ctrl_fread) {
+		__raw_writel(AR71XX_SPI_FS_GPIO, base + AR71XX_SPI_REG_FS);
+		__raw_writel(rbspi->spi_ctrl_flash, base + AR71XX_SPI_REG_CTRL);
+		__raw_writel(0, base + AR71XX_SPI_REG_FS);
+	}
+
+	return 0;
+}
+
+static int rb4xx_spi_msg(struct rb4xx_spi *rbspi, struct spi_message *m)
+{
+	struct spi_transfer *t = NULL;
+	void __iomem *base = rbspi->base;
+
+	m->status = 0;
+	if (list_empty(&m->transfers))
+		return -1;
+
+	if (m->fast_read)
+		if (rb4xx_spi_read_fast(rbspi, m) == 0)
+			return -1;
+
+	__raw_writel(AR71XX_SPI_FS_GPIO, base + AR71XX_SPI_REG_FS);
+	__raw_writel(SPI_CTRL_FASTEST, base + AR71XX_SPI_REG_CTRL);
+	do_spi_init(m->spi);
+
+	list_for_each_entry(t, &m->transfers, transfer_list) {
+		int len;
+
+		len = rb4xx_spi_txrx(base, t);
+		if (len != t->len) {
+			m->status = -EMSGSIZE;
+			break;
+		}
+		m->actual_length += len;
+
+		if (t->cs_change) {
+			if (list_is_last(&t->transfer_list, &m->transfers)) {
+				/* wait for continuation */
+				return m->spi->chip_select;
+			}
+			do_spi_finish(base);
+			ndelay(100);
+		}
+	}
+
+	do_spi_finish(base);
+	__raw_writel(rbspi->spi_ctrl_flash, base + AR71XX_SPI_REG_CTRL);
+	__raw_writel(0, base + AR71XX_SPI_REG_FS);
+	return -1;
+}
+
+static void rb4xx_spi_process_queue_locked(struct rb4xx_spi *rbspi,
+					   unsigned long *flags)
+{
+	int cs = rbspi->cs_wait;
+
+	rbspi->busy = 1;
+	while (!list_empty(&rbspi->queue)) {
+		struct spi_message *m;
+
+		list_for_each_entry(m, &rbspi->queue, queue)
+			if (cs < 0 || cs == m->spi->chip_select)
+				break;
+
+		if (&m->queue == &rbspi->queue)
+			break;
+
+		list_del_init(&m->queue);
+		spin_unlock_irqrestore(&rbspi->lock, *flags);
+
+		cs = rb4xx_spi_msg(rbspi, m);
+		m->complete(m->context);
+
+		spin_lock_irqsave(&rbspi->lock, *flags);
+	}
+
+	rbspi->cs_wait = cs;
+	rbspi->busy = 0;
+
+	if (cs >= 0) {
+		/* TODO: add timer to unlock cs after 1s inactivity */
+	}
+}
+
+static int rb4xx_spi_transfer(struct spi_device *spi,
+			      struct spi_message *m)
+{
+	struct rb4xx_spi *rbspi = spi_master_get_devdata(spi->master);
+	unsigned long flags;
+
+	m->actual_length = 0;
+	m->status = -EINPROGRESS;
+
+	spin_lock_irqsave(&rbspi->lock, flags);
+	list_add_tail(&m->queue, &rbspi->queue);
+	if (rbspi->busy ||
+	    (rbspi->cs_wait >= 0 && rbspi->cs_wait != m->spi->chip_select)) {
+		/* job will be done later */
+		spin_unlock_irqrestore(&rbspi->lock, flags);
+		return 0;
+	}
+
+	/* process job in current context */
+	rb4xx_spi_process_queue_locked(rbspi, &flags);
+	spin_unlock_irqrestore(&rbspi->lock, flags);
+
+	return 0;
+}
+
+static int rb4xx_spi_setup(struct spi_device *spi)
+{
+	struct rb4xx_spi *rbspi = spi_master_get_devdata(spi->master);
+	unsigned long flags;
+
+	if (spi->mode & ~(SPI_CS_HIGH)) {
+		dev_err(&spi->dev, "mode %x not supported\n",
+			(unsigned) spi->mode);
+		return -EINVAL;
+	}
+
+	if (spi->bits_per_word != 8 && spi->bits_per_word != 0) {
+		dev_err(&spi->dev, "bits_per_word %u not supported\n",
+			(unsigned) spi->bits_per_word);
+		return -EINVAL;
+	}
+
+	spin_lock_irqsave(&rbspi->lock, flags);
+	if (rbspi->cs_wait == spi->chip_select && !rbspi->busy) {
+		rbspi->cs_wait = -1;
+		rb4xx_spi_process_queue_locked(rbspi, &flags);
+	}
+	spin_unlock_irqrestore(&rbspi->lock, flags);
+
+	return 0;
+}
+
+static unsigned get_spi_ctrl(struct rb4xx_spi *rbspi, unsigned hz_max,
+			     const char *name)
+{
+	unsigned div;
+
+	div = (rbspi->ahb_freq - 1) / (2 * hz_max);
+
+	/*
+	 * CPU has a bug at (div == 0) - first bit read is random
+	 */
+	if (div == 0)
+		++div;
+
+	if (name) {
+		unsigned ahb_khz = (rbspi->ahb_freq + 500) / 1000;
+		unsigned div_real = 2 * (div + 1);
+		pr_debug("rb4xx: %s SPI clock %u kHz (AHB %u kHz / %u)\n",
+		       name,
+		       ahb_khz / div_real,
+		       ahb_khz, div_real);
+	}
+
+	return SPI_CTRL_FASTEST + div;
+}
+
+static int rb4xx_spi_probe(struct platform_device *pdev)
+{
+	struct spi_master *master;
+	struct rb4xx_spi *rbspi;
+	struct resource *r;
+	int err = 0;
+
+	master = spi_alloc_master(&pdev->dev, sizeof(*rbspi));
+	if (master == NULL) {
+		dev_err(&pdev->dev, "no memory for spi_master\n");
+		err = -ENOMEM;
+		goto err_out;
+	}
+
+	master->bus_num = 0;
+	master->num_chipselect = 3;
+	master->setup = rb4xx_spi_setup;
+	master->transfer = rb4xx_spi_transfer;
+
+	rbspi = spi_master_get_devdata(master);
+
+	rbspi->ahb_clk = clk_get(&pdev->dev, "ahb");
+	if (IS_ERR(rbspi->ahb_clk)) {
+		err = PTR_ERR(rbspi->ahb_clk);
+		goto err_put_master;
+	}
+
+	err = clk_enable(rbspi->ahb_clk);
+	if (err)
+		goto err_clk_put;
+
+	rbspi->ahb_freq = clk_get_rate(rbspi->ahb_clk);
+	if (!rbspi->ahb_freq) {
+		err = -EINVAL;
+		goto err_clk_disable;
+	}
+
+	platform_set_drvdata(pdev, rbspi);
+
+	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (r == NULL) {
+		err = -ENOENT;
+		goto err_clk_disable;
+	}
+
+	rbspi->base = ioremap(r->start, r->end - r->start + 1);
+	if (!rbspi->base) {
+		err = -ENXIO;
+		goto err_clk_disable;
+	}
+
+	rbspi->master = master;
+	rbspi->spi_ctrl_flash = get_spi_ctrl(rbspi, SPI_FLASH_HZ, "FLASH");
+	rbspi->spi_ctrl_fread = get_spi_ctrl(rbspi, SPI_CPLD_HZ, "CPLD");
+	rbspi->cs_wait = -1;
+
+	spin_lock_init(&rbspi->lock);
+	INIT_LIST_HEAD(&rbspi->queue);
+
+	err = spi_register_master(master);
+	if (err) {
+		dev_err(&pdev->dev, "failed to register SPI master\n");
+		goto err_iounmap;
+	}
+
+	return 0;
+
+err_iounmap:
+	iounmap(rbspi->base);
+err_clk_disable:
+	clk_disable(rbspi->ahb_clk);
+err_clk_put:
+	clk_put(rbspi->ahb_clk);
+err_put_master:
+	platform_set_drvdata(pdev, NULL);
+	spi_master_put(master);
+err_out:
+	return err;
+}
+
+static int rb4xx_spi_remove(struct platform_device *pdev)
+{
+	struct rb4xx_spi *rbspi = platform_get_drvdata(pdev);
+
+	iounmap(rbspi->base);
+	clk_disable(rbspi->ahb_clk);
+	clk_put(rbspi->ahb_clk);
+	platform_set_drvdata(pdev, NULL);
+	spi_master_put(rbspi->master);
+
+	return 0;
+}
+
+static struct platform_driver rb4xx_spi_drv = {
+	.probe		= rb4xx_spi_probe,
+	.remove		= rb4xx_spi_remove,
+	.driver		= {
+		.name	= DRV_NAME,
+		.owner	= THIS_MODULE,
+	},
+};
+
+static int __init rb4xx_spi_init(void)
+{
+	return platform_driver_register(&rb4xx_spi_drv);
+}
+subsys_initcall(rb4xx_spi_init);
+
+static void __exit rb4xx_spi_exit(void)
+{
+	platform_driver_unregister(&rb4xx_spi_drv);
+}
+
+module_exit(rb4xx_spi_exit);
+
+MODULE_DESCRIPTION(DRV_DESC);
+MODULE_VERSION(DRV_VERSION);
+MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>");
+MODULE_LICENSE("GPL v2");
-- 
1.8.5.3

