[PATCH linux v2 2/3] spi: aspeed: Handle custom decoding ranges

[Cédric Le Goater <clg@xxxxxxxx>]

The "ranges" property predefines settings for the decoding ranges of
each CS. If found in the DT, the driver applies the settings at probe
time. The default behavior is to set the decoding range of each CS
using the flash device size when the spi slave is setup.

Cc: Naresh Solanki <naresh.solanki@xxxxxxxxxxxxx>
Cc: Chin-Ting Kuo <chin-ting_kuo@xxxxxxxxxxxxxx>
Signed-off-by: Cédric Le Goater <clg@xxxxxxxx>
---
 drivers/spi/spi-aspeed-smc.c | 65 +++++++++++++++++++++++++++++++++++-
 1 file changed, 64 insertions(+), 1 deletion(-)

diff --git a/drivers/spi/spi-aspeed-smc.c b/drivers/spi/spi-aspeed-smc.c
index b90571396a60..75e1d08bbd00 100644
--- a/drivers/spi/spi-aspeed-smc.c
+++ b/drivers/spi/spi-aspeed-smc.c
@@ -96,6 +96,7 @@ struct aspeed_spi {
 	u32			 ahb_base_phy;
 	u32			 ahb_window_size;
 	struct device		*dev;
+	bool                     fixed_windows;
 
 	struct clk		*clk;
 	u32			 clk_freq;
@@ -382,6 +383,7 @@ static const char *aspeed_spi_get_name(struct spi_mem *mem)
 
 struct aspeed_spi_window {
 	u32 cs;
+	u32 reg;
 	u32 offset;
 	u32 size;
 };
@@ -396,6 +398,7 @@ static void aspeed_spi_get_windows(struct aspeed_spi *aspi,
 	for (cs = 0; cs < aspi->data->max_cs; cs++) {
 		reg_val = readl(aspi->regs + CE0_SEGMENT_ADDR_REG + cs * 4);
 		windows[cs].cs = cs;
+		windows[cs].reg = reg_val;
 		windows[cs].size = data->segment_end(aspi, reg_val) -
 			data->segment_start(aspi, reg_val);
 		windows[cs].offset = data->segment_start(aspi, reg_val) - aspi->ahb_base_phy;
@@ -572,7 +575,8 @@ static int aspeed_spi_dirmap_create(struct spi_mem_dirmap_desc *desc)
 	if (op->data.dir != SPI_MEM_DATA_IN)
 		return -EOPNOTSUPP;
 
-	aspeed_spi_chip_adjust_window(chip, desc->info.offset, desc->info.length);
+	if (!aspi->fixed_windows)
+		aspeed_spi_chip_adjust_window(chip, desc->info.offset, desc->info.length);
 
 	if (desc->info.length > chip->ahb_window_size)
 		dev_warn(aspi->dev, "CE%d window (%dMB) too small for mapping",
@@ -712,6 +716,61 @@ static void aspeed_spi_enable(struct aspeed_spi *aspi, bool enable)
 		aspeed_spi_chip_enable(aspi, cs, enable);
 }
 
+static int aspeed_spi_chip_read_ranges(struct device_node *node, struct aspeed_spi *aspi)
+{
+	const char *range_prop = "ranges";
+	struct property *prop;
+	struct aspeed_spi_window ranges[ASPEED_SPI_MAX_NUM_CS];
+	int prop_size;
+	int count;
+	int ret;
+	int i;
+
+	prop = of_find_property(node, range_prop, &prop_size);
+	if (!prop)
+		return 0;
+
+	count = prop_size / sizeof(*ranges);
+	if (count > aspi->data->max_cs) {
+		dev_err(aspi->dev, "invalid '%s' property %d\n", range_prop, count);
+		return -EINVAL;
+	}
+
+	if (count < aspi->data->max_cs)
+		dev_dbg(aspi->dev, "'%s' property does not cover all CE\n",
+			range_prop);
+
+	ret = of_property_read_u32_array(node, range_prop, (u32 *)ranges, count * 4);
+	if (ret)
+		return ret;
+
+	dev_info(aspi->dev, "Using preset decoding ranges\n");
+	for (i = 0; i < count; i++) {
+		struct aspeed_spi_window *win = &ranges[i];
+
+		if (win->cs > aspi->data->max_cs) {
+			dev_err(aspi->dev, "CE%d range is invalid", win->cs);
+			return -EINVAL;
+		}
+
+		/* Trim top bit of the address to keep offset */
+		win->offset &= aspi->ahb_window_size - 1;
+
+		/* Minimal check */
+		if (win->offset + win->size > aspi->ahb_window_size) {
+			dev_warn(aspi->dev, "CE%d range is too large", win->cs);
+				return -EINVAL;
+		}
+
+		ret = aspeed_spi_set_window(aspi, win);
+		if (ret)
+			return ret;
+	}
+
+	aspi->fixed_windows = true;
+	return 0;
+}
+
 static int aspeed_spi_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
@@ -767,6 +826,10 @@ static int aspeed_spi_probe(struct platform_device *pdev)
 		return ret;
 	}
 
+	ret = aspeed_spi_chip_read_ranges(dev->of_node, aspi);
+	if (ret)
+		return ret;
+
 	/* IRQ is for DMA, which the driver doesn't support yet */
 
 	ctlr->mode_bits = SPI_RX_DUAL | SPI_TX_DUAL | data->mode_bits;
-- 
2.37.3