openadk/target/mips/dragino-ms14s/patches/3.14.17/0020-spi-ath79-add-fast-flash-read-support.patch

From c4388a57860440e23c9654f4de2f515433e685a1 Mon Sep 17 00:00:00 2001
From: Phil Sutter <phil@nwl.cc>
Date: Tue, 13 May 2014 04:12:35 +0200
Subject: [PATCH] spi-ath79: add fast flash read support

---
 .../include/asm/mach-ath79/ath79_spi_platform.h    |   1 +
 drivers/spi/spi-ath79.c                            | 124 ++++++++++++++++++++-
 2 files changed, 120 insertions(+), 5 deletions(-)

diff --git a/arch/mips/include/asm/mach-ath79/ath79_spi_platform.h b/arch/mips/include/asm/mach-ath79/ath79_spi_platform.h
index aa2283e..65369fe 100644
--- a/arch/mips/include/asm/mach-ath79/ath79_spi_platform.h
+++ b/arch/mips/include/asm/mach-ath79/ath79_spi_platform.h
@@ -18,6 +18,7 @@ struct ath79_spi_platform_data {
 
 struct ath79_spi_controller_data {
 	unsigned	gpio;
+	bool is_flash;
 };
 
 #endif /* _ATH79_SPI_PLATFORM_H */
diff --git a/drivers/spi/spi-ath79.c b/drivers/spi/spi-ath79.c
index c3b2fb9..a26a6a4 100644
--- a/drivers/spi/spi-ath79.c
+++ b/drivers/spi/spi-ath79.c
@@ -35,6 +35,11 @@
 #define ATH79_SPI_RRW_DELAY_FACTOR	12000
 #define MHZ				(1000 * 1000)
 
+enum ath79_spi_state {
+	ATH79_SPI_STATE_WAIT_CMD = 0,
+	ATH79_SPI_STATE_WAIT_READ,
+};
+
 struct ath79_spi {
 	struct spi_bitbang	bitbang;
 	u32			ioc_base;
@@ -42,6 +47,11 @@ struct ath79_spi {
 	void __iomem		*base;
 	struct clk		*clk;
 	unsigned		rrw_delay;
+
+	enum ath79_spi_state	state;
+	u32			clk_div;
+	unsigned long 		read_addr;
+	unsigned long		ahb_rate;
 };
 
 static inline u32 ath79_spi_rr(struct ath79_spi *sp, unsigned reg)
@@ -104,9 +114,6 @@ static void ath79_spi_enable(struct ath79_spi *sp)
 	/* save CTRL register */
 	sp->reg_ctrl = ath79_spi_rr(sp, AR71XX_SPI_REG_CTRL);
 	sp->ioc_base = ath79_spi_rr(sp, AR71XX_SPI_REG_IOC);
-
-	/* TODO: setup speed? */
-	ath79_spi_wr(sp, AR71XX_SPI_REG_CTRL, 0x43);
 }
 
 static void ath79_spi_disable(struct ath79_spi *sp)
@@ -203,6 +210,110 @@ static u32 ath79_spi_txrx_mode0(struct spi_device *spi, unsigned nsecs,
 	return ath79_spi_rr(sp, AR71XX_SPI_REG_RDS);
 }
 
+static int ath79_spi_do_read_flash_data(struct spi_device *spi,
+					struct spi_transfer *t)
+{
+	struct ath79_spi *sp = ath79_spidev_to_sp(spi);
+
+	/* disable GPIO mode */
+	ath79_spi_wr(sp, AR71XX_SPI_REG_FS, 0);
+
+	memcpy_fromio(t->rx_buf, sp->base + sp->read_addr, t->len);
+
+	/* enable GPIO mode */
+	ath79_spi_wr(sp, AR71XX_SPI_REG_FS, AR71XX_SPI_FS_GPIO);
+
+	/* restore IOC register */
+	ath79_spi_wr(sp, AR71XX_SPI_REG_IOC, sp->ioc_base);
+
+	return t->len;
+}
+
+static int ath79_spi_do_read_flash_cmd(struct spi_device *spi,
+				       struct spi_transfer *t)
+{
+	struct ath79_spi *sp = ath79_spidev_to_sp(spi);
+	int len;
+	const u8 *p;
+
+	sp->read_addr = 0;
+
+	len = t->len - 1;
+	p = t->tx_buf;
+
+	while (len--) {
+		p++;
+		sp->read_addr <<= 8;
+		sp->read_addr |= *p;
+	}
+
+	return t->len;
+}
+
+static bool ath79_spi_is_read_cmd(struct spi_device *spi,
+				 struct spi_transfer *t)
+{
+	return t->type == SPI_TRANSFER_FLASH_READ_CMD;
+}
+
+static bool ath79_spi_is_data_read(struct spi_device *spi,
+				  struct spi_transfer *t)
+{
+	return t->type == SPI_TRANSFER_FLASH_READ_DATA;
+}
+
+static int ath79_spi_txrx_bufs(struct spi_device *spi, struct spi_transfer *t)
+{
+	struct ath79_spi *sp = ath79_spidev_to_sp(spi);
+	int ret;
+
+	switch (sp->state) {
+	case ATH79_SPI_STATE_WAIT_CMD:
+		if (ath79_spi_is_read_cmd(spi, t)) {
+			ret = ath79_spi_do_read_flash_cmd(spi, t);
+			sp->state = ATH79_SPI_STATE_WAIT_READ;
+		} else {
+			ret = spi_bitbang_bufs(spi, t);
+		}
+		break;
+
+	case ATH79_SPI_STATE_WAIT_READ:
+		if (ath79_spi_is_data_read(spi, t)) {
+			ret = ath79_spi_do_read_flash_data(spi, t);
+		} else {
+			dev_warn(&spi->dev, "flash data read expected\n");
+			ret = -EIO;
+		}
+		sp->state = ATH79_SPI_STATE_WAIT_CMD;
+		break;
+
+	default:
+		BUG();
+	}
+
+	return ret;
+}
+
+static int ath79_spi_setup_transfer(struct spi_device *spi,
+				    struct spi_transfer *t)
+{
+	struct ath79_spi *sp = ath79_spidev_to_sp(spi);
+	struct ath79_spi_controller_data *cdata;
+	int ret;
+
+	ret = spi_bitbang_setup_transfer(spi, t);
+	if (ret)
+		return ret;
+
+	cdata = spi->controller_data;
+	if (cdata->is_flash)
+		sp->bitbang.txrx_bufs = ath79_spi_txrx_bufs;
+	else
+		sp->bitbang.txrx_bufs = spi_bitbang_bufs;
+
+	return ret;
+}
+
 static int ath79_spi_probe(struct platform_device *pdev)
 {
 	struct spi_master *master;
@@ -223,6 +334,8 @@ static int ath79_spi_probe(struct platform_device *pdev)
 
 	pdata = dev_get_platdata(&pdev->dev);
 
+	sp->state = ATH79_SPI_STATE_WAIT_CMD;
+
 	master->bits_per_word_mask = SPI_BPW_RANGE_MASK(1, 32);
 	master->setup = ath79_spi_setup;
 	master->cleanup = ath79_spi_cleanup;
@@ -234,7 +347,7 @@ static int ath79_spi_probe(struct platform_device *pdev)
 	sp->bitbang.master = master;
 	sp->bitbang.chipselect = ath79_spi_chipselect;
 	sp->bitbang.txrx_word[SPI_MODE_0] = ath79_spi_txrx_mode0;
-	sp->bitbang.setup_transfer = spi_bitbang_setup_transfer;
+	sp->bitbang.setup_transfer = ath79_spi_setup_transfer;
 	sp->bitbang.flags = SPI_CS_HIGH;
 
 	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
@@ -259,7 +372,8 @@ static int ath79_spi_probe(struct platform_device *pdev)
 	if (ret)
 		goto err_put_master;
 
-	rate = DIV_ROUND_UP(clk_get_rate(sp->clk), MHZ);
+	sp->ahb_rate = clk_get_rate(sp->clk);
+	rate = DIV_ROUND_UP(sp->ahb_rate, MHZ);
 	if (!rate) {
 		ret = -EINVAL;
 		goto err_clk_disable;
-- 
1.8.5.3