linux-kernel - [PATCH 1/3] spi: spi-microchip-core: Add support for GPIO based CS

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Date: Thu, 2 May 2024 15:34:08 +0100
From: Prajna Rajendra Kumar <prajna.rajendrakumar@...rochip.com>
To: Mark Brown <broonie@...nel.org>
CC: Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
	<linux-riscv@...ts.infradead.org>, <linux-spi@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <devicetree@...r.kernel.org>, Conor Dooley
	<conor.dooley@...rochip.com>, Daire McNamara <daire.mcnamara@...rochip.com>,
	<valentina.fernandezalanis@...rochip.com>, Prajna Rajendra Kumar
	<prajna.rajendrakumar@...rochip.com>
Subject: [PATCH 1/3] spi: spi-microchip-core: Add support for GPIO based CS

The SPI controller within the PolarFire SoC is capable of handling
multiple CS, but only one CS line is wired in the MSS. Therefore,
use GPIO descriptors to configure additional CS lines.

Signed-off-by: Prajna Rajendra Kumar <prajna.rajendrakumar@...rochip.com>
---
 drivers/spi/spi-microchip-core.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/spi/spi-microchip-core.c b/drivers/spi/spi-microchip-core.c
index 634364c7cfe6..71886c27bca3 100644
--- a/drivers/spi/spi-microchip-core.c
+++ b/drivers/spi/spi-microchip-core.c
@@ -258,6 +258,9 @@ static int mchp_corespi_setup(struct spi_device *spi)
 	struct mchp_corespi *corespi = spi_controller_get_devdata(spi->controller);
 	u32 reg;
 
+	if (spi->cs_gpiod)
+		return 0;
+
 	/*
 	 * Active high targets need to be specifically set to their inactive
 	 * states during probe by adding them to the "control group" & thus
@@ -516,6 +519,7 @@ static int mchp_corespi_probe(struct platform_device *pdev)
 
 	host->num_chipselect = num_cs;
 	host->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH;
+	host->use_gpio_descriptors = true;
 	host->setup = mchp_corespi_setup;
 	host->bits_per_word_mask = SPI_BPW_MASK(8);
 	host->transfer_one = mchp_corespi_transfer_one;
-- 
2.25.1