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From:   Andrew Jeffery <andrew@aj.id.au>
To:     joel@jms.id.au
Cc:     linux-arm-kernel@lists.infradead.org,
        linux-aspeed@lists.ozlabs.org, linux-kernel@vger.kernel.org
Subject: [PATCH] soc: aspeed: Fail probe of lpc-ctrl if reserved memory is not aligned
Date:   Mon,  2 Dec 2019 15:13:47 +1030
Message-Id: <20191202044347.14508-1-andrew@aj.id.au>
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Sender: linux-kernel-owner@vger.kernel.org
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Alignment is a hardware constraint of the LPC2AHB bridge, and misaligned
reserved memory will present as corrupted data.

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
---
 drivers/soc/aspeed/aspeed-lpc-ctrl.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/drivers/soc/aspeed/aspeed-lpc-ctrl.c b/drivers/soc/aspeed/aspeed-lpc-ctrl.c
index 01ed21e8bfee..fec17948cda0 100644
--- a/drivers/soc/aspeed/aspeed-lpc-ctrl.c
+++ b/drivers/soc/aspeed/aspeed-lpc-ctrl.c
@@ -4,6 +4,7 @@
  */
 
 #include <linux/clk.h>
+#include <linux/log2.h>
 #include <linux/mfd/syscon.h>
 #include <linux/miscdevice.h>
 #include <linux/mm.h>
@@ -241,6 +242,18 @@ static int aspeed_lpc_ctrl_probe(struct platform_device *pdev)
 
 		lpc_ctrl->mem_size = resource_size(&resm);
 		lpc_ctrl->mem_base = resm.start;
+
+		if (!is_power_of_2(lpc_ctrl->mem_size)) {
+			dev_err(dev, "Reserved memory size must be a power of 2, got %zu\n",
+			       (size_t)lpc_ctrl->mem_size);
+			return -EINVAL;
+		}
+
+		if (!IS_ALIGNED(lpc_ctrl->mem_base, lpc_ctrl->mem_size)) {
+			dev_err(dev, "Reserved memory must be naturally aligned for size %zu\n",
+			       (size_t)lpc_ctrl->mem_size);
+			return -EINVAL;
+		}
 	}
 
 	lpc_ctrl->regmap = syscon_node_to_regmap(
-- 
2.20.1