[Patch v2 2/2] spi: nxp_fspi: Implement errata workaround for LS1028A

[Kuldeep Singh]

Errata ERR050568 description says that "Flash access by FlexSPI AHB
command may not work with platform frequency equal to 300 MHz" on
LS1028A.

By default, smaller length reads(equal to RX FIFO size) are done by IP
bus and larger length reads using AHB bus. For adding errata workaround,
use IP bus to read entire flash contents and disable AHB path when
platform frequency is 300Mhz.

Signed-off-by: Kuldeep Singh <kuldeep.singh at nxp.com>
Reviewed-by: Jagan Teki <jagan at amarulasolutions.com>
---
v2:
- Rebase to top of tree
- Resolve buildman error as imx6ul report compilation failure by
  guarding changes under CONFIG_FSL_LAYERSCAPE flag.

 drivers/spi/nxp_fspi.c | 53 ++++++++++++++++++++++++++++++++++++++----
 1 file changed, 48 insertions(+), 5 deletions(-)

diff --git a/drivers/spi/nxp_fspi.c b/drivers/spi/nxp_fspi.c
index e1b3d2d77b..9030504bc7 100644
--- a/drivers/spi/nxp_fspi.c
+++ b/drivers/spi/nxp_fspi.c
@@ -41,6 +41,11 @@
 #include <spi.h>
 #include <spi-mem.h>
 #include <asm/io.h>
+#ifdef CONFIG_FSL_LAYERSCAPE
+#include <asm/arch/clock.h>
+#include <asm/arch/soc.h>
+#include <asm/arch/speed.h>
+#endif
 #include <linux/bitops.h>
 #include <linux/kernel.h>
 #include <linux/sizes.h>
@@ -315,7 +320,7 @@ struct nxp_fspi_devtype_data {
 	bool little_endian;
 };
 
-static const struct nxp_fspi_devtype_data lx2160a_data = {
+static struct nxp_fspi_devtype_data lx2160a_data = {
 	.rxfifo = SZ_512,       /* (64  * 64 bits)  */
 	.txfifo = SZ_1K,        /* (128 * 64 bits)  */
 	.ahb_buf_size = SZ_2K,  /* (256 * 64 bits)  */
@@ -323,7 +328,7 @@ static const struct nxp_fspi_devtype_data lx2160a_data = {
 	.little_endian = true,  /* little-endian    */
 };
 
-static const struct nxp_fspi_devtype_data imx8mm_data = {
+static struct nxp_fspi_devtype_data imx8mm_data = {
 	.rxfifo = SZ_512,       /* (64  * 64 bits)  */
 	.txfifo = SZ_1K,        /* (128 * 64 bits)  */
 	.ahb_buf_size = SZ_2K,  /* (256 * 64 bits)  */
@@ -338,7 +343,7 @@ struct nxp_fspi {
 	u32 memmap_phy;
 	u32 memmap_phy_size;
 	struct clk clk, clk_en;
-	const struct nxp_fspi_devtype_data *devtype_data;
+	struct nxp_fspi_devtype_data *devtype_data;
 };
 
 static inline int needs_ip_only(struct nxp_fspi *f)
@@ -529,8 +534,8 @@ static void nxp_fspi_prepare_lut(struct nxp_fspi *f,
 	for (i = 0; i < ARRAY_SIZE(lutval); i++)
 		fspi_writel(f, lutval[i], base + FSPI_LUT_REG(i));
 
-	dev_dbg(f->dev, "CMD[%x] lutval[0:%x \t 1:%x \t 2:%x \t 3:%x]\n",
-		op->cmd.opcode, lutval[0], lutval[1], lutval[2], lutval[3]);
+	dev_dbg(f->dev, "CMD[%x] lutval[0:%x \t 1:%x \t 2:%x \t 3:%x], size: 0x%08x\n",
+		op->cmd.opcode, lutval[0], lutval[1], lutval[2], lutval[3], op->data.nbytes);
 
 	/* lock LUT */
 	fspi_writel(f, FSPI_LUTKEY_VALUE, f->iobase + FSPI_LUTKEY);
@@ -827,6 +832,33 @@ static int nxp_fspi_adjust_op_size(struct spi_slave *slave,
 	return 0;
 }
 
+#ifdef CONFIG_FSL_LAYERSCAPE
+static void erratum_err050568(struct nxp_fspi *f)
+{
+	struct sys_info sysinfo;
+	u32 svr = 0, freq = 0;
+
+	/* Check for LS1028A variants */
+	svr = SVR_SOC_VER(get_svr());
+	if (svr != SVR_LS1017A ||
+	    svr != SVR_LS1018A ||
+	    svr != SVR_LS1027A ||
+	    svr != SVR_LS1028A) {
+		dev_dbg(f->dev, "Errata applicable only for LS1028A variants\n");
+		return;
+	}
+
+	/* Read PLL frequency */
+	get_sys_info(&sysinfo);
+	freq = sysinfo.freq_systembus / 1000000; /* Convert to MHz */
+	dev_dbg(f->dev, "svr: %08x, Frequency: %dMhz\n", svr, freq);
+
+	/* Use IP bus only if PLL is 300MHz */
+	if (freq == 300)
+		f->devtype_data->quirks |= FSPI_QUIRK_USE_IP_ONLY;
+}
+#endif
+
 static int nxp_fspi_default_setup(struct nxp_fspi *f)
 {
 	void __iomem *base = f->iobase;
@@ -847,6 +879,17 @@ static int nxp_fspi_default_setup(struct nxp_fspi *f)
 		return ret;
 #endif
 
+#ifdef CONFIG_FSL_LAYERSCAPE
+	/*
+	 * ERR050568: Flash access by FlexSPI AHB command may not work with
+	 * platform frequency equal to 300 MHz on LS1028A.
+	 * LS1028A reuses LX2160A compatible entry. Make errata applicable for
+	 * Layerscape LS1028A platform family.
+	 */
+	if (device_is_compatible(f->dev, "nxp,lx2160a-fspi"))
+		erratum_err050568(f);
+#endif
+
 	/* Reset the module */
 	/* w1c register, wait unit clear */
 	ret = fspi_readl_poll_tout(f, f->iobase + FSPI_MCR0,
-- 
2.25.1