[PATCH 2/5] ARM: at91: add SDRAMC driver for memory detection

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

We already have support to read back memory size from the SDRAM
controller on older AT91 processor via the at91_get_sdram_size()
function, but that's mostly called from board code.

Add a proper driver that can probe the SDRAM device in the DT to
dynamically detect the memory without hardcoding.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
---
 arch/arm/mach-at91/Kconfig          |  3 ++
 arch/arm/mach-at91/Makefile         |  1 +
 arch/arm/mach-at91/sdramc.c         | 47 +++++++++++++++++++++++++++++
 include/mach/at91/at91sam9_sdramc.h |  4 +++
 4 files changed, 55 insertions(+)
 create mode 100644 arch/arm/mach-at91/sdramc.c

diff --git a/arch/arm/mach-at91/Kconfig b/arch/arm/mach-at91/Kconfig
index d2499747252d..1197e06670c7 100644
--- a/arch/arm/mach-at91/Kconfig
+++ b/arch/arm/mach-at91/Kconfig
@@ -42,6 +42,9 @@ config HAVE_AT91_I2S_MUX_CLK
 config HAVE_AT91_SAM9X60_PLL
 	bool
 
+config HAVE_AT91_SDRAMC
+	bool
+
 config HAVE_AT91_DDRAMC
 	bool
 
diff --git a/arch/arm/mach-at91/Makefile b/arch/arm/mach-at91/Makefile
index 301e0b761b26..777dc6d1aa3c 100644
--- a/arch/arm/mach-at91/Makefile
+++ b/arch/arm/mach-at91/Makefile
@@ -16,6 +16,7 @@ obj-$(CONFIG_BOOTM) += bootm-barebox.o
 obj-y += at91sam9_reset.o
 obj-y += at91sam9g45_reset.o
 obj-pbl-$(CONFIG_HAVE_AT91_DDRAMC) += ddramc.o
+obj-pbl-$(CONFIG_HAVE_AT91_SDRAMC) += sdramc.o
 pbl-$(CONFIG_AT91_MCI_PBL) +=  xload-mmc.o
 pbl-$(CONFIG_AT91_MCI_PBL) +=  at91sam9_xload_mmc.o
 
diff --git a/arch/arm/mach-at91/sdramc.c b/arch/arm/mach-at91/sdramc.c
new file mode 100644
index 000000000000..655f24ecd9ad
--- /dev/null
+++ b/arch/arm/mach-at91/sdramc.c
@@ -0,0 +1,47 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2020 Ahmad Fatoum <a.fatoum@pengutronix.de>
+ */
+
+#include <common.h>
+#include <init.h>
+#include <mach/at91/hardware.h>
+#include <asm/barebox-arm.h>
+#include <mach/at91/at91sam9_sdramc.h>
+#include <asm/memory.h>
+#include <pbl.h>
+#include <io.h>
+
+void __noreturn at91sam9260_barebox_entry(void *boarddata)
+{
+	barebox_arm_entry(AT91_CHIPSELECT_1,
+			  at91_get_sdram_size(IOMEM(AT91SAM9260_BASE_SDRAMC)),
+			  boarddata);
+}
+
+static int at91_sdramc_probe(struct device *dev)
+{
+	struct resource *iores;
+	void __iomem *base;
+
+	iores = dev_request_mem_resource(dev, 0);
+	if (IS_ERR(iores))
+		return PTR_ERR(iores);
+	base = IOMEM(iores->start);
+
+	return arm_add_mem_device("ram0", AT91_CHIPSELECT_1,
+				  at91_get_sdram_size(base));
+}
+
+static struct of_device_id at91_sdramc_dt_ids[] = {
+	{ .compatible = "atmel,at91sam9260-sdramc" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, at91_sdramc_dt_ids);
+
+static struct driver at91_sdramc_driver = {
+	.name   = "at91sam9260-sdramc",
+	.probe  = at91_sdramc_probe,
+	.of_compatible = at91_sdramc_dt_ids,
+};
+mem_platform_driver(at91_sdramc_driver);
diff --git a/include/mach/at91/at91sam9_sdramc.h b/include/mach/at91/at91sam9_sdramc.h
index a4c88b24d4a0..2ba73cd2f2dc 100644
--- a/include/mach/at91/at91sam9_sdramc.h
+++ b/include/mach/at91/at91sam9_sdramc.h
@@ -13,6 +13,8 @@
 #ifndef AT91SAM9_SDRAMC_H
 #define AT91SAM9_SDRAMC_H
 
+#include <linux/compiler.h>
+
 /* SDRAM Controller (SDRAMC) registers */
 #define AT91_SDRAMC_MR		0x00	/* SDRAM Controller Mode Register */
 #define		AT91_SDRAMC_MODE	(0xf << 0)		/* Command Mode */
@@ -268,5 +270,7 @@ static inline bool at91sam9263_is_low_power_sdram(int bank)
 	}
 }
 
+void __noreturn at91sam9260_barebox_entry(void *boarddata);
+
 #endif
 #endif
-- 
2.39.2