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From:   Krishna Yarlagadda <kyarlagadda@nvidia.com>
To:     <robh+dt@kernel.org>, <broonie@kernel.org>, <peterhuewe@gmx.de>,
        <jgg@ziepe.ca>, <jarkko@kernel.org>,
        <krzysztof.kozlowski+dt@linaro.org>, <linux-spi@vger.kernel.org>,
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CC:     <thierry.reding@gmail.com>, <jonathanh@nvidia.com>,
        <skomatineni@nvidia.com>, <ldewangan@nvidia.com>,
        Krishna Yarlagadda <kyarlagadda@nvidia.com>
Subject: [Patch V9 3/3] spi: tegra210-quad: Enable TPM wait polling
Date:   Sun, 26 Mar 2023 00:04:09 +0530
Message-ID: <20230325183409.7695-4-kyarlagadda@nvidia.com>
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Trusted Platform Module requires flow control. As defined in TPM
interface specification, client would drive MISO line at same cycle as
last address bit on MOSI.
Tegra234 and Tegra241 QSPI controllers have TPM wait state detection
feature which is enabled for TPM client devices reported in SPI device
mode bits.

Signed-off-by: Krishna Yarlagadda <kyarlagadda@nvidia.com>
---
 drivers/spi/spi-tegra210-quad.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/drivers/spi/spi-tegra210-quad.c b/drivers/spi/spi-tegra210-quad.c
index 325b4427491c..de6aafe4448c 100644
--- a/drivers/spi/spi-tegra210-quad.c
+++ b/drivers/spi/spi-tegra210-quad.c
@@ -142,6 +142,7 @@
 
 #define QSPI_GLOBAL_CONFIG			0X1a4
 #define QSPI_CMB_SEQ_EN				BIT(0)
+#define QSPI_TPM_WAIT_POLL_EN			BIT(1)
 
 #define QSPI_CMB_SEQ_ADDR			0x1a8
 #define QSPI_ADDRESS_VALUE_SET(X)		(((x) & 0xFFFF) << 0)
@@ -164,6 +165,7 @@
 struct tegra_qspi_soc_data {
 	bool has_dma;
 	bool cmb_xfer_capable;
+	bool supports_tpm;
 	unsigned int cs_count;
 };
 
@@ -1065,6 +1067,12 @@ static int tegra_qspi_combined_seq_xfer(struct tegra_qspi *tqspi,
 
 	/* Enable Combined sequence mode */
 	val = tegra_qspi_readl(tqspi, QSPI_GLOBAL_CONFIG);
+	if (spi->mode & SPI_TPM_HW_FLOW) {
+		if (tqspi->soc_data->supports_tpm)
+			val |= QSPI_TPM_WAIT_POLL_EN;
+		else
+			return -EIO;
+	}
 	val |= QSPI_CMB_SEQ_EN;
 	tegra_qspi_writel(tqspi, val, QSPI_GLOBAL_CONFIG);
 	/* Process individual transfer list */
@@ -1196,6 +1204,8 @@ static int tegra_qspi_non_combined_seq_xfer(struct tegra_qspi *tqspi,
 	/* Disable Combined sequence mode */
 	val = tegra_qspi_readl(tqspi, QSPI_GLOBAL_CONFIG);
 	val &= ~QSPI_CMB_SEQ_EN;
+	if (tqspi->soc_data->supports_tpm)
+		val &= ~QSPI_TPM_WAIT_POLL_EN;
 	tegra_qspi_writel(tqspi, val, QSPI_GLOBAL_CONFIG);
 	list_for_each_entry(transfer, &msg->transfers, transfer_list) {
 		struct spi_transfer *xfer = transfer;
@@ -1454,24 +1464,28 @@ static irqreturn_t tegra_qspi_isr_thread(int irq, void *context_data)
 static struct tegra_qspi_soc_data tegra210_qspi_soc_data = {
 	.has_dma = true,
 	.cmb_xfer_capable = false,
+	.supports_tpm = false,
 	.cs_count = 1,
 };
 
 static struct tegra_qspi_soc_data tegra186_qspi_soc_data = {
 	.has_dma = true,
 	.cmb_xfer_capable = true,
+	.supports_tpm = false,
 	.cs_count = 1,
 };
 
 static struct tegra_qspi_soc_data tegra234_qspi_soc_data = {
 	.has_dma = false,
 	.cmb_xfer_capable = true,
+	.supports_tpm = true,
 	.cs_count = 1,
 };
 
 static struct tegra_qspi_soc_data tegra241_qspi_soc_data = {
 	.has_dma = false,
 	.cmb_xfer_capable = true,
+	.supports_tpm = true,
 	.cs_count = 4,
 };
 
-- 
2.17.1