spi: fsl-espi: pre-allocate message buffer

Currently the driver allocates a 64kb buffer for each single message.
On systems with little and fragmented memory this can result in
memory allocation errors. Solve this by pre-allocating a buffer.

This patch was developed in OpenWRT long ago, however it never
made it upstream.

I slightly modified the original patch to re-initialize the buffer
at the beginning of each transfer.

Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
Signed-off-by: Felix Fietkau <nbd@nbd.name>
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

2 files changed, 19 insertions, 23 deletions

diff --git a/drivers/spi/spi-fsl-espi.c b/drivers/spi/spi-fsl-espi.c
index 16fff7237ab2..81d7416668b8 100644
--- a/drivers/spi/spi-fsl-espi.c
+++ b/drivers/spi/spi-fsl-espi.c
@@ -297,57 +297,44 @@ static void fsl_espi_do_trans(struct spi_message *m,
 static void fsl_espi_cmd_trans(struct spi_message *m,
                                 struct fsl_espi_transfer *trans, u8 *rx_buff)
 {
+        struct mpc8xxx_spi *mspi = spi_master_get_devdata(m->spi->master);
         struct spi_transfer *t;
-        u8 *local_buf;
         int i = 0;
         struct fsl_espi_transfer *espi_trans = trans;
 
-        local_buf = kzalloc(SPCOM_TRANLEN_MAX, GFP_KERNEL);
-        if (!local_buf) {
-                espi_trans->status = -ENOMEM;
-                return;
-        }
-
         list_for_each_entry(t, &m->transfers, transfer_list) {
                 if (t->tx_buf) {
-                        memcpy(local_buf + i, t->tx_buf, t->len);
+                        memcpy(mspi->local_buf + i, t->tx_buf, t->len);
                         i += t->len;
                 }
         }
 
-        espi_trans->tx_buf = local_buf;
-        espi_trans->rx_buf = local_buf;
+        espi_trans->tx_buf = mspi->local_buf;
+        espi_trans->rx_buf = mspi->local_buf;
         fsl_espi_do_trans(m, espi_trans);
 
         espi_trans->actual_length = espi_trans->len;
-        kfree(local_buf);
 }
 
 static void fsl_espi_rw_trans(struct spi_message *m,
                                 struct fsl_espi_transfer *trans, u8 *rx_buff)
 {
+        struct mpc8xxx_spi *mspi = spi_master_get_devdata(m->spi->master);
         struct spi_transfer *t;
-        u8 *local_buf;
         unsigned int tx_only = 0;
         int i = 0;
 
-        local_buf = kzalloc(SPCOM_TRANLEN_MAX, GFP_KERNEL);
-        if (!local_buf) {
-                trans->status = -ENOMEM;
-                return;
-        }
-
         list_for_each_entry(t, &m->transfers, transfer_list) {
                 if (t->tx_buf) {
-                        memcpy(local_buf + i, t->tx_buf, t->len);
+                        memcpy(mspi->local_buf + i, t->tx_buf, t->len);
                         i += t->len;
                         if (!t->rx_buf)
                                 tx_only += t->len;
                 }
         }
 
-        trans->tx_buf = local_buf;
-        trans->rx_buf = local_buf;
+        trans->tx_buf = mspi->local_buf;
+        trans->rx_buf = mspi->local_buf;
         fsl_espi_do_trans(m, trans);
 
         if (!trans->status) {
@@ -357,18 +344,19 @@ static void fsl_espi_rw_trans(struct spi_message *m,
                                trans->len - tx_only);
                 trans->actual_length += trans->len;
         }
-
-        kfree(local_buf);
 }
 
 static int fsl_espi_do_one_msg(struct spi_master *master,
                                struct spi_message *m)
 {
+        struct mpc8xxx_spi *mspi = spi_master_get_devdata(master);
         struct spi_transfer *t;
         u8 *rx_buf = NULL;
         unsigned int xfer_len = 0;
         struct fsl_espi_transfer espi_trans;
 
+        memset(mspi->local_buf, 0, SPCOM_TRANLEN_MAX);
+
         list_for_each_entry(t, &m->transfers, transfer_list) {
                 if (t->rx_buf)
                         rx_buf = t->rx_buf;
@@ -614,6 +602,13 @@ static struct spi_master * fsl_espi_probe(struct device *dev,
 
         mpc8xxx_spi = spi_master_get_devdata(master);
 
+        mpc8xxx_spi->local_buf =
+                devm_kmalloc(dev, SPCOM_TRANLEN_MAX, GFP_KERNEL);
+        if (!mpc8xxx_spi->local_buf) {
+                ret = -ENOMEM;
+                goto err_probe;
+        }
+
         mpc8xxx_spi->reg_base = devm_ioremap_resource(dev, mem);
         if (IS_ERR(mpc8xxx_spi->reg_base)) {
                 ret = PTR_ERR(mpc8xxx_spi->reg_base);
diff --git a/drivers/spi/spi-fsl-lib.h b/drivers/spi/spi-fsl-lib.h
index 84f5dcb7a897..065b9db212cf 100644
--- a/drivers/spi/spi-fsl-lib.h
+++ b/drivers/spi/spi-fsl-lib.h
@@ -30,6 +30,7 @@ struct mpc8xxx_spi {
         void *rx;
 #if IS_ENABLED(CONFIG_SPI_FSL_ESPI)
         int len;
+        u8 *local_buf;
 #endif
 
         int subblock;