linux-kernel - [Patch V4 1/3] spi: Add TPM HW flow flag

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Date:   Fri, 24 Feb 2023 21:19:39 +0530
From:   Krishna Yarlagadda <kyarlagadda@...dia.com>
To:     <robh+dt@...nel.org>, <broonie@...nel.org>, <peterhuewe@....de>,
        <jgg@...pe.ca>, <jarkko@...nel.org>,
        <krzysztof.kozlowski+dt@...aro.org>, <linux-spi@...r.kernel.org>,
        <linux-tegra@...r.kernel.org>, <linux-integrity@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
CC:     <thierry.reding@...il.com>, <jonathanh@...dia.com>,
        <skomatineni@...dia.com>, <ldewangan@...dia.com>,
        Krishna Yarlagadda <kyarlagadda@...dia.com>
Subject: [Patch V4 1/3] spi: Add TPM HW flow flag

TPM spec defines flow control over SPI. Client device can insert a wait
state on MISO when address is trasmitted by controller on MOSI. It can
work only on full duplex.
Half duplex controllers need to implement flow control in HW.
Add a flag for TPM to indicate flow control is expected in controller.

Signed-off-by: Krishna Yarlagadda <kyarlagadda@...dia.com>
---
 include/linux/spi/spi.h | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
index 988aabc31871..b88494e31239 100644
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -184,8 +184,9 @@ struct spi_device {
 	u8			chip_select;
 	u8			bits_per_word;
 	bool			rt;
-#define SPI_NO_TX	BIT(31)		/* No transmit wire */
-#define SPI_NO_RX	BIT(30)		/* No receive wire */
+#define SPI_NO_TX		BIT(31)		/* No transmit wire */
+#define SPI_NO_RX		BIT(30)		/* No receive wire */
+#define SPI_TPM_HW_FLOW		BIT(29)		/* TPM flow control */
 	/*
 	 * All bits defined above should be covered by SPI_MODE_KERNEL_MASK.
 	 * The SPI_MODE_KERNEL_MASK has the SPI_MODE_USER_MASK counterpart,
@@ -195,7 +196,7 @@ struct spi_device {
 	 * These bits must not overlap. A static assert check should make sure of that.
 	 * If adding extra bits, make sure to decrease the bit index below as well.
 	 */
-#define SPI_MODE_KERNEL_MASK	(~(BIT(30) - 1))
+#define SPI_MODE_KERNEL_MASK	(~(BIT(29) - 1))
 	u32			mode;
 	int			irq;
 	void			*controller_state;
-- 
2.17.1