linux-kernel - [PATCH v4 1/6] spi: cadence-qspi: allow FIFO depth detection

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Message-Id: <20240423-cdns-qspi-mbly-v4-1-3d2a7b535ad0@bootlin.com>
Date: Tue, 23 Apr 2024 12:01:40 +0200
From: Théo Lebrun <theo.lebrun@...tlin.com>
To: Mark Brown <broonie@...nel.org>, Rob Herring <robh+dt@...nel.org>, 
 Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>, 
 Conor Dooley <conor+dt@...nel.org>, Vaishnav Achath <vaishnav.a@...com>, 
 Thomas Bogendoerfer <tsbogend@...ha.franken.de>, 
 Rob Herring <robh@...nel.org>
Cc: linux-spi@...r.kernel.org, devicetree@...r.kernel.org, 
 linux-kernel@...r.kernel.org, linux-mips@...r.kernel.org, 
 Vladimir Kondratiev <vladimir.kondratiev@...ileye.com>, 
 Gregory CLEMENT <gregory.clement@...tlin.com>, 
 Thomas Petazzoni <thomas.petazzoni@...tlin.com>, 
 Tawfik Bayouk <tawfik.bayouk@...ileye.com>, 
 Théo Lebrun <theo.lebrun@...tlin.com>
Subject: [PATCH v4 1/6] spi: cadence-qspi: allow FIFO depth detection

If FIFO depth DT property is provided, check it matches what hardware
reports and warn otherwise. Else, use hardware provided value.

Hardware exposes FIFO depth indirectly because
CQSPI_REG_SRAMPARTITION is partially read-only.

Move probe cqspi->ddata assignment prior to cqspi_of_get_pdata() call.

Signed-off-by: Théo Lebrun <theo.lebrun@...tlin.com>
---
 drivers/spi/spi-cadence-quadspi.c | 37 ++++++++++++++++++++++++++++++-------
 1 file changed, 30 insertions(+), 7 deletions(-)

diff --git a/drivers/spi/spi-cadence-quadspi.c b/drivers/spi/spi-cadence-quadspi.c
index 9896e9fe7ffb..5a83940220a9 100644
--- a/drivers/spi/spi-cadence-quadspi.c
+++ b/drivers/spi/spi-cadence-quadspi.c
@@ -1510,8 +1510,8 @@ static int cqspi_of_get_pdata(struct cqspi_st *cqspi)
 	cqspi->is_decoded_cs = of_property_read_bool(np, "cdns,is-decoded-cs");
 
 	if (of_property_read_u32(np, "cdns,fifo-depth", &cqspi->fifo_depth)) {
-		dev_err(dev, "couldn't determine fifo-depth\n");
-		return -ENXIO;
+		/* Zero signals FIFO depth should be runtime detected. */
+		cqspi->fifo_depth = 0;
 	}
 
 	if (of_property_read_u32(np, "cdns,fifo-width", &cqspi->fifo_width)) {
@@ -1541,8 +1541,6 @@ static void cqspi_controller_init(struct cqspi_st *cqspi)
 {
 	u32 reg;
 
-	cqspi_controller_enable(cqspi, 0);
-
 	/* Configure the remap address register, no remap */
 	writel(0, cqspi->iobase + CQSPI_REG_REMAP);
 
@@ -1576,8 +1574,29 @@ static void cqspi_controller_init(struct cqspi_st *cqspi)
 		reg |= CQSPI_REG_CONFIG_DMA_MASK;
 		writel(reg, cqspi->iobase + CQSPI_REG_CONFIG);
 	}
+}
 
-	cqspi_controller_enable(cqspi, 1);
+static void cqspi_controller_detect_fifo_depth(struct cqspi_st *cqspi)
+{
+	struct device *dev = &cqspi->pdev->dev;
+	u32 reg, fifo_depth;
+
+	/*
+	 * Bits N-1:0 are writable while bits 31:N are read as zero, with 2^N
+	 * the FIFO depth.
+	 */
+	writel(U32_MAX, cqspi->iobase + CQSPI_REG_SRAMPARTITION);
+	reg = readl(cqspi->iobase + CQSPI_REG_SRAMPARTITION);
+	fifo_depth = reg + 1;
+
+	/* FIFO depth of zero means no value from devicetree was provided. */
+	if (cqspi->fifo_depth == 0) {
+		cqspi->fifo_depth = fifo_depth;
+		dev_dbg(dev, "using FIFO depth of %u\n", fifo_depth);
+	} else if (fifo_depth != cqspi->fifo_depth) {
+		dev_warn(dev, "detected FIFO depth (%u) different from config (%u)\n",
+			 fifo_depth, cqspi->fifo_depth);
+	}
 }
 
 static int cqspi_request_mmap_dma(struct cqspi_st *cqspi)
@@ -1730,6 +1749,7 @@ static int cqspi_probe(struct platform_device *pdev)
 	cqspi->pdev = pdev;
 	cqspi->host = host;
 	cqspi->is_jh7110 = false;
+	cqspi->ddata = ddata = of_device_get_match_data(dev);
 	platform_set_drvdata(pdev, cqspi);
 
 	/* Obtain configuration from OF. */
@@ -1821,8 +1841,6 @@ static int cqspi_probe(struct platform_device *pdev)
 	/* write completion is supported by default */
 	cqspi->wr_completion = true;
 
-	ddata = of_device_get_match_data(dev);
-	cqspi->ddata = ddata;
 	if (ddata) {
 		if (ddata->quirks & CQSPI_NEEDS_WR_DELAY)
 			cqspi->wr_delay = 50 * DIV_ROUND_UP(NSEC_PER_SEC,
@@ -1864,7 +1882,10 @@ static int cqspi_probe(struct platform_device *pdev)
 	}
 
 	cqspi_wait_idle(cqspi);
+	cqspi_controller_enable(cqspi, 0);
+	cqspi_controller_detect_fifo_depth(cqspi);
 	cqspi_controller_init(cqspi);
+	cqspi_controller_enable(cqspi, 1);
 	cqspi->current_cs = -1;
 	cqspi->sclk = 0;
 
@@ -1947,7 +1968,9 @@ static int cqspi_runtime_resume(struct device *dev)
 
 	clk_prepare_enable(cqspi->clk);
 	cqspi_wait_idle(cqspi);
+	cqspi_controller_enable(cqspi, 0);
 	cqspi_controller_init(cqspi);
+	cqspi_controller_enable(cqspi, 1);
 
 	cqspi->current_cs = -1;
 	cqspi->sclk = 0;

-- 
2.44.0