[PATCH 05/13] ARM: MXS: i.MX28: add autodetection of memory banks

[Roland Hieber <r.hieber@pengutronix.de>]

If the prebootloader has set up the EMI controller correctly, we can
autodetect the size of available RAM by looking at the respective
configuration registers.

Signed-off-by: Roland Hieber <r.hieber@pengutronix.de>
---
 arch/arm/mach-mxs/Makefile    |  2 +-
 arch/arm/mach-mxs/mem-imx28.c | 39 +++++++++++++++++++++++++++++++++++
 2 files changed, 40 insertions(+), 1 deletion(-)
 create mode 100644 arch/arm/mach-mxs/mem-imx28.c

diff --git a/arch/arm/mach-mxs/Makefile b/arch/arm/mach-mxs/Makefile
index e3843368c2..0761f909a1 100644
--- a/arch/arm/mach-mxs/Makefile
+++ b/arch/arm/mach-mxs/Makefile
@@ -1,7 +1,7 @@
 obj-y += imx.o iomux-imx.o power.o
 pbl-y += iomux-imx.o
 obj-$(CONFIG_ARCH_IMX23) += clocksource-imx23.o usb-imx23.o soc-imx23.o
-obj-$(CONFIG_ARCH_IMX28) += clocksource-imx28.o usb-imx28.o soc-imx28.o
+obj-$(CONFIG_ARCH_IMX28) += clocksource-imx28.o usb-imx28.o soc-imx28.o mem-imx28.o
 obj-$(CONFIG_MXS_OCOTP) += ocotp.o
 obj-$(CONFIG_MXS_CMD_BCB) += bcb.o
 pbl-y += power-init.o mem-init.o lradc-init.o
diff --git a/arch/arm/mach-mxs/mem-imx28.c b/arch/arm/mach-mxs/mem-imx28.c
new file mode 100644
index 0000000000..e827e0906f
--- /dev/null
+++ b/arch/arm/mach-mxs/mem-imx28.c
@@ -0,0 +1,39 @@
+/*
+ * Copyright (C) 2018 Pengutronix, Roland Hieber <r.hieber@pengutronix.de>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <init.h>
+#include <asm/memory.h>
+#include <mach/imx28-regs.h>
+#include <printk.h>
+
+static int mx28_add_mem(void)
+{
+	if (!of_machine_is_compatible("fsl,imx28"))
+		return 0;
+
+	int * sdramc = (int *)IMX_SDRAMC_BASE;
+
+	uint8_t columns = 12 - ((sdramc[29] >> 16) & 0b111);
+	uint8_t rows    = 15 - ((sdramc[29] >>  8) & 0b111);
+	uint8_t banks   =      ((sdramc[31] >> 16) & 0b1)  ?  8  :  4;
+	uint8_t width   = sizeof (unsigned short);
+
+	uint32_t size = (1 << columns) * (1 << rows) * banks * width;
+	pr_info("i.MX28: detected %d cols, %d rows, %d banks = %d MiB of RAM\n",
+			columns, rows, banks, size / 1024 / 1024);
+
+	arm_add_mem_device("ram0", IMX_MEMORY_BASE, size);
+
+	return 0;
+}
+mem_initcall(mx28_add_mem);
-- 
2.18.0


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