[PATCH 5.14 049/432] spi: fsi: Reduce max transfer size to 8 bytes

Greg Kroah-Hartman
2021-09-16T17:14:31Z

From: Eddie James <eajames@linux.ibm.com>

commit 34d34a56a5ea1e54a5af4f34c6ac9df724129351 upstream.

Security changes have forced the SPI controllers to be limited to
8 byte reads. Refactor the sequencing to just handle 8 bytes at a
time.

Signed-off-by: Eddie James <eajames@linux.ibm.com>
Link: https://lore.kernel.org/r/20210716133915.14697-2-eajames@linux.ibm.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/spi/spi-fsi.c | 125 ++++++++------------------------------------------
1 file changed, 22 insertions(+), 103 deletions(-)

--- a/drivers/spi/spi-fsi.c
+++ b/drivers/spi/spi-fsi.c
@@ -25,16 +25,11 @@

#define SPI_FSI_BASE 0x70000
#define SPI_FSI_INIT_TIMEOUT_MS 1000
-#define SPI_FSI_MAX_XFR_SIZE 2048
-#define SPI_FSI_MAX_XFR_SIZE_RESTRICTED 8
+#define SPI_FSI_MAX_RX_SIZE 8
+#define SPI_FSI_MAX_TX_SIZE 40

#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)
@@ -76,8 +71,6 @@ 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 {
@@ -241,7 +234,7 @@ static int fsi_spi_reset(struct fsi_spi
return fsi_spi_write_reg(ctx, SPI_FSI_STATUS, 0ULL);
}

-static int fsi_spi_sequence_add(struct fsi_spi_sequence *seq, u8 val)
+static void fsi_spi_sequence_add(struct fsi_spi_sequence *seq, u8 val)
{
/*
* Add the next byte of instruction to the 8-byte sequence register.
@@ -251,8 +244,6 @@ static int fsi_spi_sequence_add(struct f
*/
seq->data |= (u64)val << seq->bit;
seq->bit -= 8;
-
- return ((64 - seq->bit) / 8) - 2;
}

static void fsi_spi_sequence_init(struct fsi_spi_sequence *seq)
@@ -261,71 +252,11 @@ static void fsi_spi_sequence_init(struct
seq->data = 0ULL;
}

-static int fsi_spi_sequence_transfer(struct fsi_spi *ctx,
- struct fsi_spi_sequence *seq,
- struct spi_transfer *transfer)
-{
- int loops;
- int idx;
- int rc;
- u8 val = 0;
- u8 len = min(transfer->len, 8U);
- u8 rem = transfer->len % len;
-
- loops = transfer->len / len;
-
- if (transfer->tx_buf) {
- 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) {
- 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 && loops > 1) {
- dev_warn(ctx->dev,
- "Transfer too large; no branches permitted.\n");
- return -EINVAL;
- }
-
- if (loops > 1) {
- u64 cfg = SPI_FSI_COUNTER_CFG_LOOPS(loops - 1);
-
- fsi_spi_sequence_add(seq, SPI_FSI_SEQUENCE_BRANCH(idx));
-
- 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;
- } else {
- fsi_spi_write_reg(ctx, SPI_FSI_COUNTER_CFG, 0ULL);
- }
-
- if (rem)
- fsi_spi_sequence_add(seq, rem);
-
- return 0;
-}
-
static int fsi_spi_transfer_data(struct fsi_spi *ctx,
struct spi_transfer *transfer)
{
int rc = 0;
u64 status = 0ULL;
- u64 cfg = 0ULL;

if (transfer->tx_buf) {
int nb;
@@ -363,16 +294,6 @@ static int fsi_spi_transfer_data(struct
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,
@@ -439,6 +360,10 @@ static int fsi_spi_transfer_init(struct
}
} while (seq_state && (seq_state != SPI_FSI_STATUS_SEQ_STATE_IDLE));

+ rc = fsi_spi_write_reg(ctx, SPI_FSI_COUNTER_CFG, 0ULL);
+ if (rc)
+ return rc;
+
rc = fsi_spi_read_reg(ctx, SPI_FSI_CLOCK_CFG, &clock_cfg);
if (rc)
return rc;
@@ -459,6 +384,7 @@ static int fsi_spi_transfer_one_message(
{
int rc;
u8 seq_slave = SPI_FSI_SEQUENCE_SEL_SLAVE(mesg->spi->chip_select + 1);
+ unsigned int len;
struct spi_transfer *transfer;
struct fsi_spi *ctx = spi_controller_get_devdata(ctlr);

@@ -471,8 +397,7 @@ static int fsi_spi_transfer_one_message(
struct spi_transfer *next = NULL;

/* Sequencer must do shift out (tx) first. */
- if (!transfer->tx_buf ||
- transfer->len > (ctx->max_xfr_size + 8)) {
+ if (!transfer->tx_buf || transfer->len > SPI_FSI_MAX_TX_SIZE) {
rc = -EINVAL;
goto error;
}
@@ -486,9 +411,13 @@ static int fsi_spi_transfer_one_message(
fsi_spi_sequence_init(&seq);
fsi_spi_sequence_add(&seq, seq_slave);

- rc = fsi_spi_sequence_transfer(ctx, &seq, transfer);
- if (rc)
- goto error;
+ len = transfer->len;
+ while (len > 8) {
+ fsi_spi_sequence_add(&seq,
+ SPI_FSI_SEQUENCE_SHIFT_OUT(8));
+ len -= 8;
+ }
+ fsi_spi_sequence_add(&seq, SPI_FSI_SEQUENCE_SHIFT_OUT(len));

if (!list_is_last(&transfer->transfer_list,
&mesg->transfers)) {
@@ -496,7 +425,9 @@ static int fsi_spi_transfer_one_message(

/* Sequencer can only do shift in (rx) after tx. */
if (next->rx_buf) {
- if (next->len > ctx->max_xfr_size) {
+ u8 shift;
+
+ if (next->len > SPI_FSI_MAX_RX_SIZE) {
rc = -EINVAL;
goto error;
}
@@ -504,10 +435,8 @@ static int fsi_spi_transfer_one_message(
dev_dbg(ctx->dev, "Sequence rx of %d bytes.\n",
next->len);

- rc = fsi_spi_sequence_transfer(ctx, &seq,
- next);
- if (rc)
- goto error;
+ shift = SPI_FSI_SEQUENCE_SHIFT_IN(next->len);
+ fsi_spi_sequence_add(&seq, shift);
} else {
next = NULL;
}
@@ -541,9 +470,7 @@ error:

static size_t fsi_spi_max_transfer_size(struct spi_device *spi)
{
- struct fsi_spi *ctx = spi_controller_get_devdata(spi->controller);
-
- return ctx->max_xfr_size;
+ return SPI_FSI_MAX_RX_SIZE;
}

static int fsi_spi_probe(struct device *dev)
@@ -582,14 +509,6 @@ static int fsi_spi_probe(struct device *
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);