Applied "spi: spi-ti-qspi: Fix a bug when accessing non default CS" to the spi tree

[Mark Brown <broonie@kernel.org>]

The patch

   spi: spi-ti-qspi: Fix a bug when accessing non default CS

has been applied to the spi tree at

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git for-5.5

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.  

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark

From c52c91bb9aa6bd8c38dbf9776158e33038aedd43 Mon Sep 17 00:00:00 2001
From: Vignesh Raghavendra <vigneshr@ti.com>
Date: Wed, 11 Dec 2019 21:22:16 +0530
Subject: [PATCH] spi: spi-ti-qspi: Fix a bug when accessing non default CS

When switching ChipSelect from default CS0 to any other CS, driver fails
to update the bits in system control module register that control which
CS is mapped for MMIO access. This causes reads to fail when driver
tries to access QSPI flash on CS1/2/3.

Fix this by updating appropriate bits whenever active CS changes.

Reported-by: Andreas Dannenberg <dannenberg@ti.com>
Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>
Link: https://lore.kernel.org/r/20191211155216.30212-1-vigneshr@ti.com
Signed-off-by: Mark Brown <broonie@kernel.org>
---
 drivers/spi/spi-ti-qspi.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/spi/spi-ti-qspi.c b/drivers/spi/spi-ti-qspi.c
index 3cb65371ae3b..66dcb6128539 100644
--- a/drivers/spi/spi-ti-qspi.c
+++ b/drivers/spi/spi-ti-qspi.c
@@ -62,6 +62,7 @@ struct ti_qspi {
 	u32 dc;
 
 	bool mmap_enabled;
+	int current_cs;
 };
 
 #define QSPI_PID			(0x0)
@@ -487,6 +488,7 @@ static void ti_qspi_enable_memory_map(struct spi_device *spi)
 				   MEM_CS_EN(spi->chip_select));
 	}
 	qspi->mmap_enabled = true;
+	qspi->current_cs = spi->chip_select;
 }
 
 static void ti_qspi_disable_memory_map(struct spi_device *spi)
@@ -498,6 +500,7 @@ static void ti_qspi_disable_memory_map(struct spi_device *spi)
 		regmap_update_bits(qspi->ctrl_base, qspi->ctrl_reg,
 				   MEM_CS_MASK, 0);
 	qspi->mmap_enabled = false;
+	qspi->current_cs = -1;
 }
 
 static void ti_qspi_setup_mmap_read(struct spi_device *spi, u8 opcode,
@@ -543,7 +546,7 @@ static int ti_qspi_exec_mem_op(struct spi_mem *mem,
 
 	mutex_lock(&qspi->list_lock);
 
-	if (!qspi->mmap_enabled)
+	if (!qspi->mmap_enabled || qspi->current_cs != mem->spi->chip_select)
 		ti_qspi_enable_memory_map(mem->spi);
 	ti_qspi_setup_mmap_read(mem->spi, op->cmd.opcode, op->data.buswidth,
 				op->addr.nbytes, op->dummy.nbytes);
@@ -799,6 +802,7 @@ static int ti_qspi_probe(struct platform_device *pdev)
 		}
 	}
 	qspi->mmap_enabled = false;
+	qspi->current_cs = -1;
 
 	ret = devm_spi_register_master(&pdev->dev, master);
 	if (!ret)
-- 
2.20.1