[PATCH 4/6] spi: altera: use regmap instead of direct mmio register access

[Xu Yilun <yilun.xu@xxxxxxxxx>]

This patch adds support for regmap. It allows this driver to
be compatible if low layer register access method is changed
in some cases.

Signed-off-by: Matthew Gerlach <matthew.gerlach@xxxxxxxxxxxxxxx>
Signed-off-by: Wu Hao <hao.wu@xxxxxxxxx>
Signed-off-by: Xu Yilun <yilun.xu@xxxxxxxxx>
Signed-off-by: Russ Weight <russell.h.weight@xxxxxxxxx>
---
 drivers/spi/Kconfig        |   1 +
 drivers/spi/spi-altera.c   | 103 ++++++++++++++++++++++++++++++++++++---------
 include/linux/spi/altera.h |   6 +++
 3 files changed, 90 insertions(+), 20 deletions(-)

diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index 8f1f8fc..6d79fc7 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -59,6 +59,7 @@ comment "SPI Master Controller Drivers"
 
 config SPI_ALTERA
 	tristate "Altera SPI Controller"
+	select REGMAP_MMIO
 	help
 	  This is the driver for the Altera SPI Controller.
 
diff --git a/drivers/spi/spi-altera.c b/drivers/spi/spi-altera.c
index aa9d1a2..8d47c57 100644
--- a/drivers/spi/spi-altera.c
+++ b/drivers/spi/spi-altera.c
@@ -44,7 +44,6 @@
 #define ALTERA_SPI_MAX_CS		32
 
 struct altera_spi {
-	void __iomem *base;
 	int irq;
 	int len;
 	int count;
@@ -54,8 +53,45 @@ struct altera_spi {
 	/* data buffers */
 	const unsigned char *tx;
 	unsigned char *rx;
+
+	struct regmap *regmap;
+	u32 base;
+
+	struct device *dev;
+};
+
+static const struct regmap_config spi_altera_config = {
+	.reg_bits = 32,
+	.reg_stride = 4,
+	.val_bits = 32,
+	.fast_io = true,
 };
 
+static int altr_spi_writel(struct altera_spi *hw, unsigned int reg,
+			   unsigned int val)
+{
+	int ret;
+
+	ret = regmap_write(hw->regmap, hw->base + reg, val);
+	if (ret)
+		dev_err(hw->dev, "fail to write reg 0x%x val 0x%x: %d\n",
+			reg, val, ret);
+
+	return ret;
+}
+
+static int altr_spi_readl(struct altera_spi *hw, unsigned int reg,
+			  unsigned int *val)
+{
+	int ret;
+
+	ret = regmap_read(hw->regmap, hw->base + reg, val);
+	if (ret)
+		dev_err(hw->dev, "fail to read reg 0x%x: %d\n", reg, ret);
+
+	return ret;
+}
+
 static inline struct altera_spi *altera_spi_to_hw(struct spi_device *sdev)
 {
 	return spi_master_get_devdata(sdev->master);
@@ -67,12 +103,13 @@ static void altera_spi_set_cs(struct spi_device *spi, bool is_high)
 
 	if (is_high) {
 		hw->imr &= ~ALTERA_SPI_CONTROL_SSO_MSK;
-		writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
-		writel(0, hw->base + ALTERA_SPI_SLAVE_SEL);
+		altr_spi_writel(hw, ALTERA_SPI_CONTROL, hw->imr);
+		altr_spi_writel(hw, ALTERA_SPI_SLAVE_SEL, 0);
 	} else {
-		writel(BIT(spi->chip_select), hw->base + ALTERA_SPI_SLAVE_SEL);
+		altr_spi_writel(hw, ALTERA_SPI_SLAVE_SEL,
+				BIT(spi->chip_select));
 		hw->imr |= ALTERA_SPI_CONTROL_SSO_MSK;
-		writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
+		altr_spi_writel(hw, ALTERA_SPI_CONTROL, hw->imr);
 	}
 }
 
@@ -99,14 +136,14 @@ static void altera_spi_tx_word(struct altera_spi *hw)
 		}
 	}
 
-	writel(txd, hw->base + ALTERA_SPI_TXDATA);
+	altr_spi_writel(hw, ALTERA_SPI_TXDATA, txd);
 }
 
 static void altera_spi_rx_word(struct altera_spi *hw)
 {
 	unsigned int rxd;
 
-	rxd = readl(hw->base + ALTERA_SPI_RXDATA);
+	altr_spi_readl(hw, ALTERA_SPI_RXDATA, &rxd);
 	if (hw->rx) {
 		switch (hw->bytes_per_word) {
 		case 1:
@@ -133,6 +170,7 @@ static int altera_spi_txrx(struct spi_master *master,
 	struct spi_device *spi, struct spi_transfer *t)
 {
 	struct altera_spi *hw = spi_master_get_devdata(master);
+	u32 val;
 
 	hw->tx = t->tx_buf;
 	hw->rx = t->rx_buf;
@@ -143,7 +181,7 @@ static int altera_spi_txrx(struct spi_master *master,
 	if (hw->irq >= 0) {
 		/* enable receive interrupt */
 		hw->imr |= ALTERA_SPI_CONTROL_IRRDY_MSK;
-		writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
+		altr_spi_writel(hw, ALTERA_SPI_CONTROL, hw->imr);
 
 		/* send the first byte */
 		altera_spi_tx_word(hw);
@@ -151,9 +189,13 @@ static int altera_spi_txrx(struct spi_master *master,
 		while (hw->count < hw->len) {
 			altera_spi_tx_word(hw);
 
-			while (!(readl(hw->base + ALTERA_SPI_STATUS) &
-				 ALTERA_SPI_STATUS_RRDY_MSK))
+			for (;;) {
+				altr_spi_readl(hw, ALTERA_SPI_STATUS, &val);
+				if (val & ALTERA_SPI_STATUS_RRDY_MSK)
+					break;
+
 				cpu_relax();
+			}
 
 			altera_spi_rx_word(hw);
 		}
@@ -175,7 +217,7 @@ static irqreturn_t altera_spi_irq(int irq, void *dev)
 	} else {
 		/* disable receive interrupt */
 		hw->imr &= ~ALTERA_SPI_CONTROL_IRRDY_MSK;
-		writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
+		altr_spi_writel(hw, ALTERA_SPI_CONTROL, hw->imr);
 
 		spi_finalize_current_transfer(master);
 	}
@@ -188,7 +230,9 @@ static int altera_spi_probe(struct platform_device *pdev)
 	struct altera_spi_platform_data *pdata = dev_get_platdata(&pdev->dev);
 	struct altera_spi *hw;
 	struct spi_master *master;
+	void __iomem *res;
 	int err = -ENODEV;
+	u32 val;
 	u16 i;
 
 	master = spi_alloc_master(&pdev->dev, sizeof(struct altera_spi));
@@ -220,19 +264,38 @@ static int altera_spi_probe(struct platform_device *pdev)
 	master->set_cs = altera_spi_set_cs;
 
 	hw = spi_master_get_devdata(master);
+	hw->dev = &pdev->dev;
 
 	/* find and map our resources */
-	hw->base = devm_platform_ioremap_resource(pdev, 0);
-	if (IS_ERR(hw->base)) {
-		err = PTR_ERR(hw->base);
-		goto exit;
+	if (pdata && pdata->use_parent_regmap) {
+		hw->regmap = dev_get_regmap(pdev->dev.parent, NULL);
+		if (!hw->regmap) {
+			dev_err(&pdev->dev, "get regmap failed\n");
+			goto exit;
+		}
+		hw->base = pdata->regoff;
+	} else {
+		res = devm_platform_ioremap_resource(pdev, 0);
+		if (IS_ERR(res)) {
+			err = PTR_ERR(res);
+			goto exit;
+		}
+
+		hw->regmap = devm_regmap_init_mmio(&pdev->dev, res,
+						   &spi_altera_config);
+		if (IS_ERR(hw->regmap)) {
+			dev_err(&pdev->dev, "regmap mmio init failed\n");
+			err = PTR_ERR(hw->regmap);
+			goto exit;
+		}
 	}
 	/* program defaults into the registers */
 	hw->imr = 0;		/* disable spi interrupts */
-	writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
-	writel(0, hw->base + ALTERA_SPI_STATUS);	/* clear status reg */
-	if (readl(hw->base + ALTERA_SPI_STATUS) & ALTERA_SPI_STATUS_RRDY_MSK)
-		readl(hw->base + ALTERA_SPI_RXDATA);	/* flush rxdata */
+	altr_spi_writel(hw, ALTERA_SPI_CONTROL, hw->imr);
+	altr_spi_writel(hw, ALTERA_SPI_STATUS, 0);	/* clear status reg */
+	altr_spi_readl(hw, ALTERA_SPI_STATUS, &val);
+	if (val & ALTERA_SPI_STATUS_RRDY_MSK)
+		altr_spi_readl(hw, ALTERA_SPI_RXDATA, &val); /* flush rxdata */
 	/* irq is optional */
 	hw->irq = platform_get_irq(pdev, 0);
 	if (hw->irq >= 0) {
@@ -255,7 +318,7 @@ static int altera_spi_probe(struct platform_device *pdev)
 		}
 	}
 
-	dev_info(&pdev->dev, "base %p, irq %d\n", hw->base, hw->irq);
+	dev_info(&pdev->dev, "base %u, irq %d\n", hw->base, hw->irq);
 
 	return 0;
 exit:
diff --git a/include/linux/spi/altera.h b/include/linux/spi/altera.h
index 2d42641..164ab7b 100644
--- a/include/linux/spi/altera.h
+++ b/include/linux/spi/altera.h
@@ -17,6 +17,10 @@
  * @num_devices:	Number of devices that shall be added when the driver
  *			is probed.
  * @devices:		The devices to add.
+ * @use_parent_regmap:	If true, device uses parent regmap to access its
+ *			registers. Otherwise try map platform mmio resources.
+ * @regoff:		Offset of the device register base in parent regmap.
+ *			This field is ignored when use_parent_regmap == false.
  */
 struct altera_spi_platform_data {
 	u16				mode_bits;
@@ -24,6 +28,8 @@ struct altera_spi_platform_data {
 	u32				bits_per_word_mask;
 	u16				num_devices;
 	struct spi_board_info		*devices;
+	bool				use_parent_regmap;
+	u32				regoff;
 };
 
 #endif /* __LINUX_SPI_ALTERA_H */
-- 
2.7.4