[RFC PATCH 1/4] memory: tegra124-emc: Add EMC driver
Tomeu Vizoso
tomeu.vizoso at collabora.com
Mon Jun 16 06:35:10 PDT 2014
Adds functionality for registering memory bandwidth needs and setting
the EMC clock rate based on that.
Also adds API for setting floor and ceiling frequency rates.
Signed-off-by: Tomeu Vizoso <tomeu.vizoso at collabora.com>
---
.../bindings/arm/tegra/nvidia,tegra124-emc.txt | 26 ++++
drivers/memory/Kconfig | 8 +
drivers/memory/Makefile | 1 +
drivers/memory/tegra124-emc.c | 173 +++++++++++++++++++++
include/linux/platform_data/tegra_emc.h | 23 +++
5 files changed, 231 insertions(+)
create mode 100644 Documentation/devicetree/bindings/arm/tegra/nvidia,tegra124-emc.txt
create mode 100644 drivers/memory/tegra124-emc.c
diff --git a/Documentation/devicetree/bindings/arm/tegra/nvidia,tegra124-emc.txt b/Documentation/devicetree/bindings/arm/tegra/nvidia,tegra124-emc.txt
new file mode 100644
index 0000000..88e6a55
--- /dev/null
+++ b/Documentation/devicetree/bindings/arm/tegra/nvidia,tegra124-emc.txt
@@ -0,0 +1,26 @@
+Tegra124 External Memory Controller
+
+Properties:
+- compatible : Should contain "nvidia,tegra124-emc".
+- reg : Should contain the register range of the device
+- #address-cells : Should be 1
+- #size-cells : Should be 0
+- nvidia,mc : phandle to the mc bus connected to EMC.
+- clocks : phandle to EMC, EMC shared bus override, and all parent clocks.
+- clock-names : name of each clock.
+- nvidia,pmc : phandle to the PMC syscon node.
+- max-clock-frequency : optional, specifies the maximum EMC rate in kHz.
+
+Child device nodes describe the memory settings for different configurations and
+clock rates.
+
+Example:
+
+ memory-controller at 7001b000 {
+ compatible = "nvidia,tegra124-emc";
+ reg = <0x7001b000 0x1000>;
+ #address-cells = <1>;
+ #size-cells = <0>;
+ clocks = <&tegra_car TEGRA124_CLK_EMC>;
+ clock-names = "emc";
+ };
diff --git a/drivers/memory/Kconfig b/drivers/memory/Kconfig
index c59e9c9..48fa0dd 100644
--- a/drivers/memory/Kconfig
+++ b/drivers/memory/Kconfig
@@ -61,6 +61,14 @@ config TEGRA30_MC
analysis, especially for IOMMU/SMMU(System Memory Management
Unit) module.
+config TEGRA124_EMC
+ tristate "Tegra124 External Memory Controller (EMC) driver"
+ default y
+ depends on ARCH_TEGRA_124_SOC
+ help
+ This driver is for the External Memory Controller (EMC) module
+ available in Tegra124 SoCs.
+
config FSL_IFC
bool
depends on FSL_SOC
diff --git a/drivers/memory/Makefile b/drivers/memory/Makefile
index 71160a2..0b7290b 100644
--- a/drivers/memory/Makefile
+++ b/drivers/memory/Makefile
@@ -11,3 +11,4 @@ obj-$(CONFIG_FSL_IFC) += fsl_ifc.o
obj-$(CONFIG_MVEBU_DEVBUS) += mvebu-devbus.o
obj-$(CONFIG_TEGRA20_MC) += tegra20-mc.o
obj-$(CONFIG_TEGRA30_MC) += tegra30-mc.o
+obj-$(CONFIG_TEGRA124_EMC) += tegra124-emc.o
diff --git a/drivers/memory/tegra124-emc.c b/drivers/memory/tegra124-emc.c
new file mode 100644
index 0000000..b7a54a5
--- /dev/null
+++ b/drivers/memory/tegra124-emc.c
@@ -0,0 +1,173 @@
+/*
+ * Copyright (c) 2013, NVIDIA CORPORATION. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope 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/>.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/clk.h>
+#include <linux/of_platform.h>
+#include <linux/platform_data/tegra_emc.h>
+
+#define DRV_NAME "tegra124-emc"
+#define EMC_FREQ_CUTOFF_USE_130_PERCENT 100000000
+#define EMC_FREQ_CUTOFF_USE_140_PERCENT 50000000
+#define BYTES_PER_EMC_CLOCK 16
+
+struct tegra124_emc {
+ struct clk *clk;
+ unsigned long bandwidth_requests[TEGRA_EMC_CONSUMER_LAST];
+ unsigned long floor_freq;
+ unsigned long ceiling_freq;
+ /*
+ * Cannot use a mutex here because the ACTMON driver would set a floor
+ * frequency from an IRQ handler.
+ */
+ spinlock_t spinlock;
+};
+
+static struct platform_device *emc_pdev;
+
+static unsigned long tegra124_emc_bw_to_freq_req(unsigned long bw)
+{
+ return (bw + BYTES_PER_EMC_CLOCK - 1) / BYTES_PER_EMC_CLOCK;
+}
+
+static void tegra124_emc_update_rate(struct tegra124_emc *emc)
+{
+ int i;
+ struct clk *emc_master;
+ unsigned long total_bandwidth = 0;
+ unsigned long freq;
+ unsigned long flags;
+
+ spin_lock_irqsave(&emc->spinlock, flags);
+
+ for (i = 0; i < TEGRA_EMC_CONSUMER_LAST; i++)
+ total_bandwidth += emc->bandwidth_requests[i];
+
+ emc_master = clk_get_parent(emc->clk);
+ freq = tegra124_emc_bw_to_freq_req(total_bandwidth) * 1000;
+ freq = clk_round_rate(emc_master, freq);
+
+ /* XXX: Add safety margins for DVFS */
+
+ if (freq < EMC_FREQ_CUTOFF_USE_140_PERCENT)
+ total_bandwidth += 4 * total_bandwidth / 10;
+ else if (freq < EMC_FREQ_CUTOFF_USE_130_PERCENT)
+ total_bandwidth += 3 * total_bandwidth / 10;
+ else
+ total_bandwidth += total_bandwidth / 10;
+
+ freq = tegra124_emc_bw_to_freq_req(total_bandwidth) * 1000;
+ freq = max(freq, emc->floor_freq);
+ freq = min(freq, emc->ceiling_freq);
+
+ spin_unlock_irqrestore(&emc->spinlock, flags);
+
+
+ clk_set_rate(emc->clk, freq);
+}
+
+int tegra124_emc_reserve_bandwidth(unsigned int consumer, unsigned long rate)
+{
+ struct tegra124_emc *emc = platform_get_drvdata(emc_pdev);
+ unsigned long flags;
+
+ if (consumer >= TEGRA_EMC_CONSUMER_LAST) {
+ dev_err(&emc_pdev->dev, "Invalid EMC consumer ID (%u)\n", consumer);
+ return -EINVAL;
+ }
+
+ spin_lock_irqsave(&emc->spinlock, flags);
+ emc->bandwidth_requests[consumer] = rate;
+ spin_unlock_irqrestore(&emc->spinlock, flags);
+
+ tegra124_emc_update_rate(emc);
+
+ return 0;
+}
+
+void tegra124_emc_set_floor(unsigned long freq)
+{
+ struct tegra124_emc *emc = platform_get_drvdata(emc_pdev);
+ unsigned long flags;
+
+ spin_lock_irqsave(&emc->spinlock, flags);
+ emc->floor_freq = freq;
+ spin_unlock_irqrestore(&emc->spinlock, flags);
+
+ tegra124_emc_update_rate(emc);
+}
+
+void tegra124_emc_set_ceiling(unsigned long freq)
+{
+ struct tegra124_emc *emc = platform_get_drvdata(emc_pdev);
+ unsigned long flags;
+
+ spin_lock_irqsave(&emc->spinlock, flags);
+ emc->ceiling_freq = freq;
+ spin_unlock_irqrestore(&emc->spinlock, flags);
+
+ tegra124_emc_update_rate(emc);
+}
+
+static int tegra124_emc_probe(struct platform_device *pdev)
+{
+ struct tegra124_emc *emc;
+
+ emc_pdev = pdev;
+
+ emc = devm_kzalloc(&pdev->dev, sizeof(*emc), GFP_KERNEL);
+ if (emc == NULL) {
+ dev_err(&pdev->dev, "Failed to allocate private memory\n");
+ return -ENOMEM;
+ }
+
+ emc->ceiling_freq = ULONG_MAX;
+
+ emc->clk = devm_clk_get(&pdev->dev, "emc");
+ if (IS_ERR(emc->clk)) {
+ devm_kfree(&pdev->dev, emc);
+ dev_err(&pdev->dev, "Can not find EMC clock\n");
+ return -EINVAL;
+ }
+
+ spin_lock_init(&emc->spinlock);
+
+ platform_set_drvdata(emc_pdev, emc);
+
+ return 0;
+}
+
+static struct of_device_id tegra124_emc_of_match[] = {
+ { .compatible = "nvidia,tegra124-emc", },
+ { },
+};
+
+static struct platform_driver tegra124_emc_driver = {
+ .driver = {
+ .name = DRV_NAME,
+ .owner = THIS_MODULE,
+ .of_match_table = tegra124_emc_of_match,
+ },
+ .probe = tegra124_emc_probe,
+};
+
+module_platform_driver(tegra124_emc_driver);
+
+MODULE_AUTHOR("Tomeu Vizoso <tomeu.vizoso at collabora.com>");
+MODULE_DESCRIPTION("Tegra124 EMC driver");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:" DRV_NAME);
diff --git a/include/linux/platform_data/tegra_emc.h b/include/linux/platform_data/tegra_emc.h
index df67505..2967964 100644
--- a/include/linux/platform_data/tegra_emc.h
+++ b/include/linux/platform_data/tegra_emc.h
@@ -31,4 +31,27 @@ struct tegra_emc_pdata {
struct tegra_emc_table *tables;
};
+enum {
+ TEGRA_EMC_CONSUMER_DISP1 = 0,
+ TEGRA_EMC_CONSUMER_DISP2,
+ TEGRA_EMC_CONSUMER_MSENC,
+ TEGRA_EMC_CONSUMER_CAMERA,
+ TEGRA_EMC_CONSUMER_AVP,
+ TEGRA_EMC_CONSUMER_ISO,
+ TEGRA_EMC_CONSUMER_LAST
+};
+
+#ifdef CONFIG_TEGRA124_EMC
+int tegra124_emc_reserve_bandwidth(unsigned int consumer, unsigned long rate);
+void tegra124_emc_set_floor(unsigned long freq);
+void tegra124_emc_set_ceiling(unsigned long freq);
+#else
+int tegra124_emc_reserve_bandwidth(unsigned int consumer, unsigned long rate)
+{ return -ENODEV; }
+void tegra124_emc_set_floor(unsigned long freq)
+{ return; }
+void tegra124_emc_set_ceiling(unsigned long freq)
+{ return; }
+#endif
+
#endif
--
1.9.3
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