[PATCH v2 0/6] spi: Fixes for FSI-attached controller

[PATCH v2 0/6] spi: Fixes for FSI-attached controller

[Eddie James]

This series implements a number of fixes for the FSI-attached SPI
controller driver.

Changes since v1:
 - Switch to a new compatible string for the restricted version of the
   SPI controller, rather than a new boolean parameter.

Brad Bishop (3):
  spi: fsi: Handle 9 to 15 byte transfers lengths
  spi: fsi: Fix clock running too fast
  spi: fsi: Fix use of the bneq+ sequencer instruction

Eddie James (3):
  dt-bindings: fsi: fsi2spi: Add compatible string for restricted
    version
  spi: fsi: Implement restricted size for certain controllers
  spi: fsi: Check mux status before transfers

 .../devicetree/bindings/fsi/ibm,fsi2spi.yaml  |   1 +
 drivers/spi/spi-fsi.c                         | 139 ++++++++++++++----
 2 files changed, 109 insertions(+), 31 deletions(-)

-- 
2.26.2

[PATCH v2 1/6] spi: fsi: Handle 9 to 15 byte transfers lengths

[Eddie James]

From: Brad Bishop <bradleyb@fuzziesquirrel.com>

The trailing <len> - 8 bytes of transfer data in this size range is no
longer ignored.

Fixes: bbb6b2f9865b ("spi: Add FSI-attached SPI controller driver")
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
Signed-off-by: Eddie James <eajames@linux.ibm.com>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Joel Stanley <joel@jms.id.au>
---
 drivers/spi/spi-fsi.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/spi/spi-fsi.c b/drivers/spi/spi-fsi.c
index 37a3e0f8e752..8f64af0140e0 100644
--- a/drivers/spi/spi-fsi.c
+++ b/drivers/spi/spi-fsi.c
@@ -258,15 +258,15 @@ static int fsi_spi_sequence_transfer(struct fsi_spi *ctx,
 	if (loops > 1) {
 		fsi_spi_sequence_add(seq, SPI_FSI_SEQUENCE_BRANCH(idx));
 
-		if (rem)
-			fsi_spi_sequence_add(seq, rem);
-
 		rc = fsi_spi_write_reg(ctx, SPI_FSI_COUNTER_CFG,
 				       SPI_FSI_COUNTER_CFG_LOOPS(loops - 1));
 		if (rc)
 			return rc;
 	}
 
+	if (rem)
+		fsi_spi_sequence_add(seq, rem);
+
 	return 0;
 }
 
-- 
2.26.2

[PATCH v2 2/6] spi: fsi: Fix clock running too fast

[Eddie James]

From: Brad Bishop <bradleyb@fuzziesquirrel.com>

Use a clock divider tuned to a 200MHz FSI bus frequency (the maximum). Use
of the previous divider at 200MHz results in corrupt data from endpoint
devices. Ideally the clock divider would be calculated from the FSI clock,
but that would require some significant work on the FSI driver. With FSI
frequencies slower than 200MHz, the SPI clock will simply run slower, but
safely.

Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
Signed-off-by: Eddie James <eajames@linux.ibm.com>
Signed-off-by: Joel Stanley <joel@jms.id.au>
---
 drivers/spi/spi-fsi.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/spi/spi-fsi.c b/drivers/spi/spi-fsi.c
index 8f64af0140e0..559d0ff981f3 100644
--- a/drivers/spi/spi-fsi.c
+++ b/drivers/spi/spi-fsi.c
@@ -350,7 +350,7 @@ static int fsi_spi_transfer_init(struct fsi_spi *ctx)
 	u64 status = 0ULL;
 	u64 wanted_clock_cfg = SPI_FSI_CLOCK_CFG_ECC_DISABLE |
 		SPI_FSI_CLOCK_CFG_SCK_NO_DEL |
-		FIELD_PREP(SPI_FSI_CLOCK_CFG_SCK_DIV, 4);
+		FIELD_PREP(SPI_FSI_CLOCK_CFG_SCK_DIV, 19);
 
 	end = jiffies + msecs_to_jiffies(SPI_FSI_INIT_TIMEOUT_MS);
 	do {
-- 
2.26.2

[PATCH v2 3/6] spi: fsi: Fix use of the bneq+ sequencer instruction

[Eddie James]

From: Brad Bishop <bradleyb@fuzziesquirrel.com>

All of the switches in N2_count_control in the counter configuration are
required to make the branch if not equal and increment command work.
Set them when using bneq+.

A side effect of this mode requires a dummy write to TDR when both
transmitting and receiving otherwise the controller won't start shifting
receive data.

It is likely not possible to avoid TDR underrun errors in this mode and
they are harmless, so do not check for them.

Fixes: bbb6b2f9865b ("spi: Add FSI-attached SPI controller driver")
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
Signed-off-by: Eddie James <eajames@linux.ibm.com>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Joel Stanley <joel@jms.id.au>
---
 drivers/spi/spi-fsi.c | 28 +++++++++++++++++++++++++---
 1 file changed, 25 insertions(+), 3 deletions(-)

diff --git a/drivers/spi/spi-fsi.c b/drivers/spi/spi-fsi.c
index 559d0ff981f3..c31a852b6a3e 100644
--- a/drivers/spi/spi-fsi.c
+++ b/drivers/spi/spi-fsi.c
@@ -29,6 +29,10 @@
 #define SPI_FSI_ERROR			0x0
 #define SPI_FSI_COUNTER_CFG		0x1
 #define  SPI_FSI_COUNTER_CFG_LOOPS(x)	 (((u64)(x) & 0xffULL) << 32)
+#define  SPI_FSI_COUNTER_CFG_N2_RX	 BIT_ULL(8)
+#define  SPI_FSI_COUNTER_CFG_N2_TX	 BIT_ULL(9)
+#define  SPI_FSI_COUNTER_CFG_N2_IMPLICIT BIT_ULL(10)
+#define  SPI_FSI_COUNTER_CFG_N2_RELOAD	 BIT_ULL(11)
 #define SPI_FSI_CFG1			0x2
 #define SPI_FSI_CLOCK_CFG		0x3
 #define  SPI_FSI_CLOCK_CFG_MM_ENABLE	 BIT_ULL(32)
@@ -61,7 +65,7 @@
 #define  SPI_FSI_STATUS_RDR_OVERRUN	 BIT_ULL(62)
 #define  SPI_FSI_STATUS_RDR_FULL	 BIT_ULL(63)
 #define  SPI_FSI_STATUS_ANY_ERROR	 \
-	(SPI_FSI_STATUS_ERROR | SPI_FSI_STATUS_TDR_UNDERRUN | \
+	(SPI_FSI_STATUS_ERROR | \
 	 SPI_FSI_STATUS_TDR_OVERRUN | SPI_FSI_STATUS_RDR_UNDERRUN | \
 	 SPI_FSI_STATUS_RDR_OVERRUN)
 #define SPI_FSI_PORT_CTRL		0x9
@@ -238,6 +242,7 @@ static int fsi_spi_sequence_transfer(struct fsi_spi *ctx,
 	int rc;
 	u8 len = min(transfer->len, 8U);
 	u8 rem = transfer->len % len;
+	u64 cfg = 0ULL;
 
 	loops = transfer->len / len;
 
@@ -258,8 +263,14 @@ static int fsi_spi_sequence_transfer(struct fsi_spi *ctx,
 	if (loops > 1) {
 		fsi_spi_sequence_add(seq, SPI_FSI_SEQUENCE_BRANCH(idx));
 
-		rc = fsi_spi_write_reg(ctx, SPI_FSI_COUNTER_CFG,
-				       SPI_FSI_COUNTER_CFG_LOOPS(loops - 1));
+		cfg = SPI_FSI_COUNTER_CFG_LOOPS(loops - 1);
+		if (transfer->rx_buf)
+			cfg |= SPI_FSI_COUNTER_CFG_N2_RX |
+				SPI_FSI_COUNTER_CFG_N2_TX |
+				SPI_FSI_COUNTER_CFG_N2_IMPLICIT |
+				SPI_FSI_COUNTER_CFG_N2_RELOAD;
+
+		rc = fsi_spi_write_reg(ctx, SPI_FSI_COUNTER_CFG, cfg);
 		if (rc)
 			return rc;
 	}
@@ -275,6 +286,7 @@ static int fsi_spi_transfer_data(struct fsi_spi *ctx,
 {
 	int rc = 0;
 	u64 status = 0ULL;
+	u64 cfg = 0ULL;
 
 	if (transfer->tx_buf) {
 		int nb;
@@ -312,6 +324,16 @@ static int fsi_spi_transfer_data(struct fsi_spi *ctx,
 		u64 in = 0ULL;
 		u8 *rx = transfer->rx_buf;
 
+		rc = fsi_spi_read_reg(ctx, SPI_FSI_COUNTER_CFG, &cfg);
+		if (rc)
+			return rc;
+
+		if (cfg & SPI_FSI_COUNTER_CFG_N2_IMPLICIT) {
+			rc = fsi_spi_write_reg(ctx, SPI_FSI_DATA_TX, 0);
+			if (rc)
+				return rc;
+		}
+
 		while (transfer->len > recv) {
 			do {
 				rc = fsi_spi_read_reg(ctx, SPI_FSI_STATUS,
-- 
2.26.2

[PATCH v2 4/6] dt-bindings: fsi: fsi2spi: Add compatible string for restricted version

[Eddie James]

Add a compatible string for the restricted version of the SPI controller.
The restricted version cannot process sequence loop operations and
therefore has a smaller transfer size.

Signed-off-by: Eddie James <eajames@linux.ibm.com>
---
 Documentation/devicetree/bindings/fsi/ibm,fsi2spi.yaml | 1 +
 1 file changed, 1 insertion(+)

diff --git a/Documentation/devicetree/bindings/fsi/ibm,fsi2spi.yaml b/Documentation/devicetree/bindings/fsi/ibm,fsi2spi.yaml
index b26d4b4be743..fe39ea4904c1 100644
--- a/Documentation/devicetree/bindings/fsi/ibm,fsi2spi.yaml
+++ b/Documentation/devicetree/bindings/fsi/ibm,fsi2spi.yaml
@@ -19,6 +19,7 @@ properties:
   compatible:
     enum:
       - ibm,fsi2spi
+      - ibm,fsi2spi-restricted
 
   reg:
     items:
-- 
2.26.2

[PATCH v2 5/6] spi: fsi: Implement restricted size for certain controllers

[Eddie James]

Some of the FSI-attached SPI controllers cannot use the loop command in
programming the sequencer due to security requirements. Check the
devicetree compatibility that indicates this condition and restrict the
size for these controllers. Also, add more transfers directly in the
sequence up to the length of the sequence register.

Fixes: bbb6b2f9865b ("spi: Add FSI-attached SPI controller driver")
Signed-off-by: Eddie James <eajames@linux.ibm.com>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Joel Stanley <joel@jms.id.au>
---
 drivers/spi/spi-fsi.c | 65 +++++++++++++++++++++++++++++++++++--------
 1 file changed, 53 insertions(+), 12 deletions(-)

diff --git a/drivers/spi/spi-fsi.c b/drivers/spi/spi-fsi.c
index c31a852b6a3e..a702e9d7d68c 100644
--- a/drivers/spi/spi-fsi.c
+++ b/drivers/spi/spi-fsi.c
@@ -24,7 +24,8 @@
 
 #define SPI_FSI_BASE			0x70000
 #define SPI_FSI_INIT_TIMEOUT_MS		1000
-#define SPI_FSI_MAX_TRANSFER_SIZE	2048
+#define SPI_FSI_MAX_XFR_SIZE		2048
+#define SPI_FSI_MAX_XFR_SIZE_RESTRICTED	32
 
 #define SPI_FSI_ERROR			0x0
 #define SPI_FSI_COUNTER_CFG		0x1
@@ -74,6 +75,8 @@ struct fsi_spi {
 	struct device *dev;	/* SPI controller device */
 	struct fsi_device *fsi;	/* FSI2SPI CFAM engine device */
 	u32 base;
+	size_t max_xfr_size;
+	bool restricted;
 };
 
 struct fsi_spi_sequence {
@@ -209,8 +212,12 @@ static int fsi_spi_reset(struct fsi_spi *ctx)
 	if (rc)
 		return rc;
 
-	return fsi_spi_write_reg(ctx, SPI_FSI_CLOCK_CFG,
-				 SPI_FSI_CLOCK_CFG_RESET2);
+	rc = fsi_spi_write_reg(ctx, SPI_FSI_CLOCK_CFG,
+			       SPI_FSI_CLOCK_CFG_RESET2);
+	if (rc)
+		return rc;
+
+	return fsi_spi_write_reg(ctx, SPI_FSI_STATUS, 0ULL);
 }
 
 static int fsi_spi_sequence_add(struct fsi_spi_sequence *seq, u8 val)
@@ -218,8 +225,8 @@ static int fsi_spi_sequence_add(struct fsi_spi_sequence *seq, u8 val)
 	/*
 	 * Add the next byte of instruction to the 8-byte sequence register.
 	 * Then decrement the counter so that the next instruction will go in
-	 * the right place. Return the number of "slots" left in the sequence
-	 * register.
+	 * the right place. Return the index of the slot we just filled in the
+	 * sequence register.
 	 */
 	seq->data |= (u64)val << seq->bit;
 	seq->bit -= 8;
@@ -237,9 +244,11 @@ static int fsi_spi_sequence_transfer(struct fsi_spi *ctx,
 				     struct fsi_spi_sequence *seq,
 				     struct spi_transfer *transfer)
 {
+	bool docfg = false;
 	int loops;
 	int idx;
 	int rc;
+	u8 val = 0;
 	u8 len = min(transfer->len, 8U);
 	u8 rem = transfer->len % len;
 	u64 cfg = 0ULL;
@@ -247,22 +256,42 @@ static int fsi_spi_sequence_transfer(struct fsi_spi *ctx,
 	loops = transfer->len / len;
 
 	if (transfer->tx_buf) {
-		idx = fsi_spi_sequence_add(seq,
-					   SPI_FSI_SEQUENCE_SHIFT_OUT(len));
+		val = SPI_FSI_SEQUENCE_SHIFT_OUT(len);
+		idx = fsi_spi_sequence_add(seq, val);
+
 		if (rem)
 			rem = SPI_FSI_SEQUENCE_SHIFT_OUT(rem);
 	} else if (transfer->rx_buf) {
-		idx = fsi_spi_sequence_add(seq,
-					   SPI_FSI_SEQUENCE_SHIFT_IN(len));
+		val = SPI_FSI_SEQUENCE_SHIFT_IN(len);
+		idx = fsi_spi_sequence_add(seq, val);
+
 		if (rem)
 			rem = SPI_FSI_SEQUENCE_SHIFT_IN(rem);
 	} else {
 		return -EINVAL;
 	}
 
+	if (ctx->restricted) {
+		const int eidx = rem ? 5 : 6;
+
+		while (loops > 1 && idx <= eidx) {
+			idx = fsi_spi_sequence_add(seq, val);
+			loops--;
+			docfg = true;
+		}
+
+		if (loops > 1) {
+			dev_warn(ctx->dev, "No sequencer slots; aborting.\n");
+			return -EINVAL;
+		}
+	}
+
 	if (loops > 1) {
 		fsi_spi_sequence_add(seq, SPI_FSI_SEQUENCE_BRANCH(idx));
+		docfg = true;
+	}
 
+	if (docfg) {
 		cfg = SPI_FSI_COUNTER_CFG_LOOPS(loops - 1);
 		if (transfer->rx_buf)
 			cfg |= SPI_FSI_COUNTER_CFG_N2_RX |
@@ -273,6 +302,8 @@ static int fsi_spi_sequence_transfer(struct fsi_spi *ctx,
 		rc = fsi_spi_write_reg(ctx, SPI_FSI_COUNTER_CFG, cfg);
 		if (rc)
 			return rc;
+	} else {
+		fsi_spi_write_reg(ctx, SPI_FSI_COUNTER_CFG, 0ULL);
 	}
 
 	if (rem)
@@ -429,7 +460,7 @@ static int fsi_spi_transfer_one_message(struct spi_controller *ctlr,
 
 		/* Sequencer must do shift out (tx) first. */
 		if (!transfer->tx_buf ||
-		    transfer->len > SPI_FSI_MAX_TRANSFER_SIZE) {
+		    transfer->len > (ctx->max_xfr_size + 8)) {
 			rc = -EINVAL;
 			goto error;
 		}
@@ -453,7 +484,7 @@ static int fsi_spi_transfer_one_message(struct spi_controller *ctlr,
 
 			/* Sequencer can only do shift in (rx) after tx. */
 			if (next->rx_buf) {
-				if (next->len > SPI_FSI_MAX_TRANSFER_SIZE) {
+				if (next->len > ctx->max_xfr_size) {
 					rc = -EINVAL;
 					goto error;
 				}
@@ -498,7 +529,9 @@ static int fsi_spi_transfer_one_message(struct spi_controller *ctlr,
 
 static size_t fsi_spi_max_transfer_size(struct spi_device *spi)
 {
-	return SPI_FSI_MAX_TRANSFER_SIZE;
+	struct fsi_spi *ctx = spi_controller_get_devdata(spi->controller);
+
+	return ctx->max_xfr_size;
 }
 
 static int fsi_spi_probe(struct device *dev)
@@ -546,6 +579,14 @@ static int fsi_spi_probe(struct device *dev)
 		ctx->fsi = fsi;
 		ctx->base = base + SPI_FSI_BASE;
 
+		if (of_device_is_compatible(np, "ibm,fsi2spi-restricted")) {
+			ctx->restricted = true;
+			ctx->max_xfr_size = SPI_FSI_MAX_XFR_SIZE_RESTRICTED;
+		} else {
+			ctx->restricted = false;
+			ctx->max_xfr_size = SPI_FSI_MAX_XFR_SIZE;
+		}
+
 		rc = devm_spi_register_controller(dev, ctlr);
 		if (rc)
 			spi_controller_put(ctlr);
-- 
2.26.2

[PATCH v2 6/6] spi: fsi: Check mux status before transfers

[Eddie James]

The SPI controllers are not accessible if the mux isn't set. Therefore,
check the mux status before starting a transfer and fail out if it isn't
set.

Signed-off-by: Eddie James <eajames@linux.ibm.com>
Signed-off-by: Joel Stanley <joel@jms.id.au>
---
 drivers/spi/spi-fsi.c | 40 +++++++++++++++++++++++++++-------------
 1 file changed, 27 insertions(+), 13 deletions(-)

diff --git a/drivers/spi/spi-fsi.c b/drivers/spi/spi-fsi.c
index a702e9d7d68c..8a440c7078ef 100644
--- a/drivers/spi/spi-fsi.c
+++ b/drivers/spi/spi-fsi.c
@@ -12,6 +12,7 @@
 
 #define FSI_ENGID_SPI			0x23
 #define FSI_MBOX_ROOT_CTRL_8		0x2860
+#define  FSI_MBOX_ROOT_CTRL_8_SPI_MUX	 0xf0000000
 
 #define FSI2SPI_DATA0			0x00
 #define FSI2SPI_DATA1			0x04
@@ -84,6 +85,26 @@ struct fsi_spi_sequence {
 	u64 data;
 };
 
+static int fsi_spi_check_mux(struct fsi_device *fsi, struct device *dev)
+{
+	int rc;
+	u32 root_ctrl_8;
+	__be32 root_ctrl_8_be;
+
+	rc = fsi_slave_read(fsi->slave, FSI_MBOX_ROOT_CTRL_8, &root_ctrl_8_be,
+			    sizeof(root_ctrl_8_be));
+	if (rc)
+		return rc;
+
+	root_ctrl_8 = be32_to_cpu(root_ctrl_8_be);
+	dev_dbg(dev, "Root control register 8: %08x\n", root_ctrl_8);
+	if ((root_ctrl_8 & FSI_MBOX_ROOT_CTRL_8_SPI_MUX) ==
+	     FSI_MBOX_ROOT_CTRL_8_SPI_MUX)
+		return 0;
+
+	return -ENOLINK;
+}
+
 static int fsi_spi_check_status(struct fsi_spi *ctx)
 {
 	int rc;
@@ -449,11 +470,15 @@ static int fsi_spi_transfer_init(struct fsi_spi *ctx)
 static int fsi_spi_transfer_one_message(struct spi_controller *ctlr,
 					struct spi_message *mesg)
 {
-	int rc = 0;
+	int rc;
 	u8 seq_slave = SPI_FSI_SEQUENCE_SEL_SLAVE(mesg->spi->chip_select + 1);
 	struct spi_transfer *transfer;
 	struct fsi_spi *ctx = spi_controller_get_devdata(ctlr);
 
+	rc = fsi_spi_check_mux(ctx->fsi, ctx->dev);
+	if (rc)
+		return rc;
+
 	list_for_each_entry(transfer, &mesg->transfers, transfer_list) {
 		struct fsi_spi_sequence seq;
 		struct spi_transfer *next = NULL;
@@ -537,24 +562,13 @@ static size_t fsi_spi_max_transfer_size(struct spi_device *spi)
 static int fsi_spi_probe(struct device *dev)
 {
 	int rc;
-	u32 root_ctrl_8;
 	struct device_node *np;
 	int num_controllers_registered = 0;
 	struct fsi_device *fsi = to_fsi_dev(dev);
 
-	/*
-	 * Check the SPI mux before attempting to probe. If the mux isn't set
-	 * then the SPI controllers can't access their slave devices.
-	 */
-	rc = fsi_slave_read(fsi->slave, FSI_MBOX_ROOT_CTRL_8, &root_ctrl_8,
-			    sizeof(root_ctrl_8));
+	rc = fsi_spi_check_mux(fsi, dev);
 	if (rc)
-		return rc;
-
-	if (!root_ctrl_8) {
-		dev_dbg(dev, "SPI mux not set, aborting probe.\n");
 		return -ENODEV;
-	}
 
 	for_each_available_child_of_node(dev->of_node, np) {
 		u32 base;
-- 
2.26.2

Re: [PATCH v2 0/6] spi: Fixes for FSI-attached controller

[Mark Brown]

On Wed, 9 Sep 2020 17:28:51 -0500, Eddie James wrote:
> This series implements a number of fixes for the FSI-attached SPI
> controller driver.
> 
> Changes since v1:
>  - Switch to a new compatible string for the restricted version of the
>    SPI controller, rather than a new boolean parameter.
> 
> [...]

Applied to

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

Thanks!

[1/6] spi: fsi: Handle 9 to 15 byte transfers lengths
      commit: 2b3cef0fc757bd06ed9b83bd4c436bfa55f47370
[2/6] spi: fsi: Fix clock running too fast
      commit: 0b546bbe9474ff23e6843916ad6d567f703b2396
[3/6] spi: fsi: Fix use of the bneq+ sequencer instruction
      commit: 7909eebb2bea7fdbb2de0aa794cf29843761ed5b
[4/6] spi: fsi: fsi2spi: Add compatible string for restricted version
      commit: b0e4dfe93714b21e2fa9b03819b3e99383e5c330
[5/6] spi: fsi: Implement restricted size for certain controllers
      commit: 49c9fc1d7c101eceaddb655e4f0e062b0c8f403b
[6/6] spi: fsi: Check mux status before transfers
      commit: 9211a441e60686eec2ebd8f7bd65c4f780416404

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