Re: [PATCH 4/9] ARM: zynq: PM: Enable DDR self-refresh and clock stop
From: Michal Simek <hidden>
Date: 2014-08-21 12:25:37
Also in:
linux-arm-kernel, linux-pm, lkml
On 08/20/2014 10:41 PM, Soren Brinkmann wrote:
quoted hunk ↗ jump to hunk
The DDR controller can detect idle periods and leverage low power features like self-refresh and clock stop. When new requests occur, the DDRC resumes normal operation. Signed-off-by: Soren Brinkmann <redacted> --- arch/arm/mach-zynq/Makefile | 2 +- arch/arm/mach-zynq/common.c | 1 + arch/arm/mach-zynq/common.h | 2 ++ arch/arm/mach-zynq/pm.c | 84 +++++++++++++++++++++++++++++++++++++++++++++ 4 files changed, 88 insertions(+), 1 deletion(-) create mode 100644 arch/arm/mach-zynq/pm.cdiff --git a/arch/arm/mach-zynq/Makefile b/arch/arm/mach-zynq/Makefile index 1b25d92ebf22..820dff6e1eba 100644 --- a/arch/arm/mach-zynq/Makefile +++ b/arch/arm/mach-zynq/Makefile@@ -3,7 +3,7 @@ # # Common support -obj-y := common.o slcr.o +obj-y := common.o slcr.o pm.o CFLAGS_REMOVE_hotplug.o =-march=armv6k CFLAGS_hotplug.o =-Wa,-march=armv7-a -mcpu=cortex-a9 obj-$(CONFIG_HOTPLUG_CPU) += hotplug.odiff --git a/arch/arm/mach-zynq/common.c b/arch/arm/mach-zynq/common.c index 3cb7c198615a..6bd13e5ce6b7 100644 --- a/arch/arm/mach-zynq/common.c +++ b/arch/arm/mach-zynq/common.c@@ -101,6 +101,7 @@ static int __init zynq_get_revision(void) static void __init zynq_init_late(void) { zynq_core_pm_init(); + zynq_pm_late_init(); } /**diff --git a/arch/arm/mach-zynq/common.h b/arch/arm/mach-zynq/common.h index 596ef0b5067c..87945fa2a179 100644 --- a/arch/arm/mach-zynq/common.h +++ b/arch/arm/mach-zynq/common.h@@ -40,6 +40,8 @@ extern void __iomem *zynq_scu_base; /* Hotplug */ extern void zynq_platform_cpu_die(unsigned int cpu); +int zynq_pm_late_init(void); + static inline void zynq_core_pm_init(void) { /* A9 clock gating */diff --git a/arch/arm/mach-zynq/pm.c b/arch/arm/mach-zynq/pm.c new file mode 100644 index 000000000000..19955917aac8 --- /dev/null +++ b/arch/arm/mach-zynq/pm.c@@ -0,0 +1,84 @@ +/* + * Zynq power management + * + * Copyright (C) 2012 - 2014 Xilinx + * + * Sören Brinkmann <soren.brinkmann@xilinx.com> + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, either version 2 of the License, or + * (at your option) any later version. + * + * 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. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see <http://www.gnu.org/licenses/>.
IRC this paragraph is not necessary and can be just removed.
+ */ + +#include <linux/io.h> +#include <linux/of_address.h> +#include <linux/of_device.h> +#include "common.h" + +/* register offsets */ +#define DDRC_CTRL_REG1_OFFS 0x60 +#define DDRC_DRAM_PARAM_REG3_OFFS 0x20 + +/* bitfields */ +#define DDRC_CLOCKSTOP_MASK BIT(23) +#define DDRC_SELFREFRESH_MASK BIT(12) + +static void __iomem *ddrc_base; + +/** + * zynq_pm_ioremap() - Create IO mappings + * @comp: DT compatible string + * Returns a pointer to the mapped memory or NULL. + * + * Remap the memory region for a compatible DT node. + */
[linux]$ ./scripts/kernel-doc -man -v arch/arm/mach-zynq/pm.c > /dev/null Info(arch/arm/mach-zynq/pm.c:38): Scanning doc for Warning(arch/arm/mach-zynq/pm.c:45): No description found for return value of 'zynq_pm_ioremap'
+static void __iomem *zynq_pm_ioremap(const char *comp)
+{
+ struct device_node *np;
+ void __iomem *base = NULL;
+
+ np = of_find_compatible_node(NULL, NULL, comp);
+ if (np) {
+ base = of_iomap(np, 0);
+ of_node_put(np);
+ } else {
+ pr_warn("%s: no compatible node found for '%s'\n", __func__,
+ comp);
+ }
+
+ return base;
+}
+
+int __init zynq_pm_late_init(void)kernel doc will be nice to have here.
+{
+ u32 reg;
+
+ ddrc_base = zynq_pm_ioremap("xlnx,zynq-ddrc-a05");
+ if (!ddrc_base) {
+ pr_warn("%s: Unable to map DDRC IO memory.\n", __func__);
+ } else {
+ /*
+ * Enable DDRC self-refresh and clock stop features. The HW
+ * takes care of entering/exiting the correct modes depending
+ * on activity state.
+ */
+ reg = readl(ddrc_base + DDRC_CTRL_REG1_OFFS);
+ reg |= DDRC_SELFREFRESH_MASK;
+ writel(reg, ddrc_base + DDRC_CTRL_REG1_OFFS);
+
+ reg = readl(ddrc_base + DDRC_DRAM_PARAM_REG3_OFFS);
+ reg |= DDRC_CLOCKSTOP_MASK;
+ writel(reg, ddrc_base + DDRC_DRAM_PARAM_REG3_OFFS);
+ }
+
+ return 0;You are not using this return value that's why I would just remove it and change function return type to void. Thanks, Michal
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