[PATCH v2] mmc: arm_pl180: Limit data transfer to U16_MAX

[cmax@mailbox.org]

From: Maximilian Brune <maximilian.brune@9elements.com>

Currently fetching files bigger that cause a data transfer greater than
U16_MAX fails.

The reason is that the specification defines the datalength register
as a 16 bit wide register, but in u-boot it is used as if it is an
32 bit register. Therefore values greater than U16_MAX cause an
infinite loop inside u-boot. U-boot expects to get more data from
interface/hardware then it will ever get and therefore inifintely waits
for more data that will never come.

Signed-off-by: Maximilian Brune <maximilian.brune@9elements.com>
Cc: Peng Fan <peng.fan@nxp.com>
Cc: Jaehoon Chung <jh80.chung@samsung.com>
---
 drivers/mmc/arm_pl180_mmci.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/mmc/arm_pl180_mmci.c b/drivers/mmc/arm_pl180_mmci.c
index 5cf5502ed5..cad73ea106 100644
--- a/drivers/mmc/arm_pl180_mmci.c
+++ b/drivers/mmc/arm_pl180_mmci.c
@@ -231,6 +231,7 @@ static int do_data_transfer(struct mmc *dev,
 	u32 blksz = 0;
 	u32 data_ctrl = 0;
 	u32 data_len = (u32) (data->blocks * data->blocksize);
+	assert(data_len < U16_MAX); /* should be ensured by arm_pl180_get_b_max */
 
 	if (!host->version2) {
 		blksz = (ffs(data->blocksize) - 1);
@@ -358,6 +359,14 @@ static int  host_set_ios(struct mmc *dev)
 	return 0;
 }
 
+static int arm_pl180_get_b_max(struct udevice *dev, void *dst, lbaint_t blkcnt)
+{
+	struct mmc_uclass_priv *upriv = dev_get_uclass_priv(dev);
+	struct mmc *mmc = upriv->mmc;
+
+	return U16_MAX / mmc->read_bl_len;
+}
+
 #ifndef CONFIG_DM_MMC
 /* MMC uses open drain drivers in the enumeration phase */
 static int mmc_host_reset(struct mmc *dev)
@@ -373,6 +382,7 @@ static const struct mmc_ops arm_pl180_mmci_ops = {
 	.send_cmd = host_request,
 	.set_ios = host_set_ios,
 	.init = mmc_host_reset,
+	.get_b_max = arm_pl180_get_b_max,
 };
 
 /*
@@ -531,6 +541,7 @@ static const struct dm_mmc_ops arm_pl180_dm_mmc_ops = {
 	.send_cmd = dm_host_request,
 	.set_ios = dm_host_set_ios,
 	.get_cd = dm_mmc_getcd,
+	.get_b_max = arm_pl180_get_b_max,
 };
 
 static int arm_pl180_mmc_of_to_plat(struct udevice *dev)
-- 
2.44.0