[PATCH linux 4/5] spi: aspeed: Handle custom decoding ranges

[Cédric Le Goater]

"ranges" predefines settings of the decoding ranges for 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 at 9elements.com>
Cc: Chin-Ting Kuo <chin-ting_kuo at aspeedtech.com>
Signed-off-by: Cédric Le Goater <clg at kaod.org>
---
 drivers/spi/spi-aspeed-smc.c | 63 +++++++++++++++++++++++++++++++++++-
 1 file changed, 62 insertions(+), 1 deletion(-)

diff --git a/drivers/spi/spi-aspeed-smc.c b/drivers/spi/spi-aspeed-smc.c
index 1611c354c31f..791cbf753a85 100644
--- a/drivers/spi/spi-aspeed-smc.c
+++ b/drivers/spi/spi-aspeed-smc.c
@@ -101,6 +101,7 @@ struct aspeed_spi {
 	u32			 clk_freq;
 
 	struct aspeed_spi_chip	 chips[ASPEED_SPI_MAX_NUM_CS];
+	bool                     fixed_windows;
 };
 
 static u32 aspeed_spi_get_io_mode(const struct spi_mem_op *op)
@@ -574,7 +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",
@@ -749,6 +751,61 @@ static const struct attribute_group aspeed_spi_attribute_group = {
 	.attrs = aspeed_spi_attributes
 };
 
+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;
@@ -806,6 +863,10 @@ 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;
-- 
2.35.3