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SubjectRe: [PATCH V3 6/6] bus: Add support for Tegra Generic Memory Interface
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On 27/10/16 15:01, Mirza Krak wrote:
> From: Mirza Krak <mirza.krak@gmail.com>
>
> The Generic Memory Interface bus can be used to connect high-speed
> devices such as NOR flash, FPGAs, DSPs...
>
> Signed-off-by: Mirza Krak <mirza.krak@gmail.com>
> Tested-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>
> Tested-on: Colibri T20/T30 on EvalBoard V3.x and GMI-Memory Board
> ---
>
> Changes in v2:
> - Fixed some checkpatch errors
> - Re-ordered probe to get rid of local variables
> - Moved of_platform_default_populate call to the end of probe
> - Use the timing and configuration properties from the child device
> - Added warning if more then 1 child device exist
>
> Changes in v3:
> - added helper function to disable the controller which is used in remove and
> on error.
> - Added logic to parse CS# from "ranges" property with fallback to "reg"
> property
>
> drivers/bus/Kconfig | 8 ++
> drivers/bus/Makefile | 1 +
> drivers/bus/tegra-gmi.c | 267 ++++++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 276 insertions(+)
> create mode 100644 drivers/bus/tegra-gmi.c
>
> diff --git a/drivers/bus/Kconfig b/drivers/bus/Kconfig
> index 4ed7d26..2e75a7f 100644
> --- a/drivers/bus/Kconfig
> +++ b/drivers/bus/Kconfig
> @@ -141,6 +141,14 @@ config TEGRA_ACONNECT
> Driver for the Tegra ACONNECT bus which is used to interface with
> the devices inside the Audio Processing Engine (APE) for Tegra210.
>
> +config TEGRA_GMI
> + tristate "Tegra Generic Memory Interface bus driver"
> + depends on ARCH_TEGRA
> + help
> + Driver for the Tegra Generic Memory Interface bus which can be used
> + to attach devices such as NOR, UART, FPGA and more.
> +
> +

Nit-pick ... only one additional line above is needed to be consistent
with the rest of the file.

> config UNIPHIER_SYSTEM_BUS
> tristate "UniPhier System Bus driver"
> depends on ARCH_UNIPHIER && OF
> diff --git a/drivers/bus/Makefile b/drivers/bus/Makefile
> index ac84cc4..34e2bab 100644
> --- a/drivers/bus/Makefile
> +++ b/drivers/bus/Makefile
> @@ -18,5 +18,6 @@ obj-$(CONFIG_OMAP_OCP2SCP) += omap-ocp2scp.o
> obj-$(CONFIG_SUNXI_RSB) += sunxi-rsb.o
> obj-$(CONFIG_SIMPLE_PM_BUS) += simple-pm-bus.o
> obj-$(CONFIG_TEGRA_ACONNECT) += tegra-aconnect.o
> +obj-$(CONFIG_TEGRA_GMI) += tegra-gmi.o
> obj-$(CONFIG_UNIPHIER_SYSTEM_BUS) += uniphier-system-bus.o
> obj-$(CONFIG_VEXPRESS_CONFIG) += vexpress-config.o
> diff --git a/drivers/bus/tegra-gmi.c b/drivers/bus/tegra-gmi.c
> new file mode 100644
> index 0000000..dd9623e
> --- /dev/null
> +++ b/drivers/bus/tegra-gmi.c
> @@ -0,0 +1,267 @@
> +/*
> + * Driver for NVIDIA Generic Memory Interface
> + *
> + * Copyright (C) 2016 Host Mobility AB. All rights reserved.
> + *
> + * This file is licensed under the terms of the GNU General Public
> + * License version 2. This program is licensed "as is" without any
> + * warranty of any kind, whether express or implied.
> + */
> +#include <linux/clk.h>
> +#include <linux/delay.h>
> +#include <linux/io.h>
> +#include <linux/module.h>
> +#include <linux/of_device.h>
> +#include <linux/reset.h>
> +
> +#define TEGRA_GMI_CONFIG 0x00
> +#define TEGRA_GMI_CONFIG_GO BIT(31)
> +#define TEGRA_GMI_BUS_WIDTH_32BIT BIT(30)
> +#define TEGRA_GMI_MUX_MODE BIT(28)
> +#define TEGRA_GMI_RDY_BEFORE_DATA BIT(24)
> +#define TEGRA_GMI_RDY_ACTIVE_HIGH BIT(23)
> +#define TEGRA_GMI_ADV_ACTIVE_HIGH BIT(22)
> +#define TEGRA_GMI_OE_ACTIVE_HIGH BIT(21)
> +#define TEGRA_GMI_CS_ACTIVE_HIGH BIT(20)
> +#define TEGRA_GMI_CS_SELECT(x) ((x & 0x7) << 4)
> +
> +#define TEGRA_GMI_TIMING0 0x10
> +#define TEGRA_GMI_MUXED_WIDTH(x) ((x & 0xf) << 12)
> +#define TEGRA_GMI_HOLD_WIDTH(x) ((x & 0xf) << 8)
> +#define TEGRA_GMI_ADV_WIDTH(x) ((x & 0xf) << 4)
> +#define TEGRA_GMI_CE_WIDTH(x) (x & 0xf)
> +
> +#define TEGRA_GMI_TIMING1 0x14
> +#define TEGRA_GMI_WE_WIDTH(x) ((x & 0xff) << 16)
> +#define TEGRA_GMI_OE_WIDTH(x) ((x & 0xff) << 8)
> +#define TEGRA_GMI_WAIT_WIDTH(x) (x & 0xff)
> +
> +struct tegra_gmi_priv {
> + void __iomem *base;
> + struct reset_control *rst;
> + struct clk *clk;
> +
> + u32 snor_config;
> + u32 snor_timing0;
> + u32 snor_timing1;
> +};
> +
> +static void tegra_gmi_disable(struct tegra_gmi_priv *priv)
> +{
> + u32 config;
> +
> + /* stop GMI operation */
> + config = readl(priv->base + TEGRA_GMI_CONFIG);
> + config &= ~TEGRA_GMI_CONFIG_GO;
> + writel(config, priv->base + TEGRA_GMI_CONFIG);
> +
> + reset_control_assert(priv->rst);
> + clk_disable_unprepare(priv->clk);
> +}
> +
> +static void tegra_gmi_init(struct device *dev, struct tegra_gmi_priv *priv)
> +{
> + writel(priv->snor_timing0, priv->base + TEGRA_GMI_TIMING0);
> + writel(priv->snor_timing1, priv->base + TEGRA_GMI_TIMING1);
> +
> + priv->snor_config |= TEGRA_GMI_CONFIG_GO;
> + writel(priv->snor_config, priv->base + TEGRA_GMI_CONFIG);
> +}
> +
> +static int tegra_gmi_parse_dt(struct device *dev, struct tegra_gmi_priv *priv)
> +{
> + struct device_node *child = of_get_next_available_child(dev->of_node,
> + NULL);
> + u32 property, ranges[4];
> + int ret;
> +
> + if (!child) {
> + dev_warn(dev, "no child nodes found\n");
> + return 0;

Don't we want to return an error here? Otherwise, we will call
tegra_gmi_init() with an invalid configuration.

> + }
> +
> + /*
> + * We currently only support one child device due to lack of
> + * chip-select address decoding. Which means that we only have one
> + * chip-select line from the GMI controller.
> + */
> + if (of_get_child_count(dev->of_node) > 1)
> + dev_warn(dev, "only one child device is supported.");
> +
> + if (of_property_read_bool(child, "nvidia,snor-data-width-32bit"))
> + priv->snor_config |= TEGRA_GMI_BUS_WIDTH_32BIT;
> +
> + if (of_property_read_bool(child, "nvidia,snor-mux-mode"))
> + priv->snor_config |= TEGRA_GMI_MUX_MODE;
> +
> + if (of_property_read_bool(child, "nvidia,snor-rdy-active-before-data"))
> + priv->snor_config |= TEGRA_GMI_RDY_BEFORE_DATA;
> +
> + if (of_property_read_bool(child, "nvidia,snor-rdy-inv"))
> + priv->snor_config |= TEGRA_GMI_RDY_ACTIVE_HIGH;
> +
> + if (of_property_read_bool(child, "nvidia,snor-adv-inv"))
> + priv->snor_config |= TEGRA_GMI_ADV_ACTIVE_HIGH;
> +
> + if (of_property_read_bool(child, "nvidia,snor-oe-inv"))
> + priv->snor_config |= TEGRA_GMI_OE_ACTIVE_HIGH;
> +
> + if (of_property_read_bool(child, "nvidia,snor-cs-inv"))
> + priv->snor_config |= TEGRA_GMI_CS_ACTIVE_HIGH;
> +
> + /* Decode the CS# */
> + ret = of_property_read_u32_array(child, "ranges", ranges, 4);
> + if (ret < 0) {
> + /* Invalid binding */
> + if (ret == -EOVERFLOW) {
> + dev_err(dev, "invalid ranges length\n");
> + goto error_cs_decode;
> + }
> +
> + /*
> + * If we reach here it means that the child node has an empty
> + * ranges or it does not exist at all. Attempt to decode the
> + * CS# from the reg property instead.
> + */
> + ret = of_property_read_u32(child, "reg", &property);
> + if (ret < 0) {
> + dev_err(dev, "no reg property found\n");
> + goto error_cs_decode;
> + }
> + } else {
> + property = ranges[1];
> + }
> +
> + priv->snor_config |= TEGRA_GMI_CS_SELECT(property);

Should we make sure the CS is a valid value before setting?

> +
> + /* The default values that are provided below are reset values */
> + if (!of_property_read_u32(child, "nvidia,snor-muxed-width", &property))
> + priv->snor_timing0 |= TEGRA_GMI_MUXED_WIDTH(property);
> + else
> + priv->snor_timing0 |= TEGRA_GMI_MUXED_WIDTH(1);
> +
> + if (!of_property_read_u32(child, "nvidia,snor-hold-width", &property))
> + priv->snor_timing0 |= TEGRA_GMI_HOLD_WIDTH(property);
> + else
> + priv->snor_timing0 |= TEGRA_GMI_HOLD_WIDTH(1);
> +
> + if (!of_property_read_u32(child, "nvidia,snor-adv-width", &property))
> + priv->snor_timing0 |= TEGRA_GMI_ADV_WIDTH(property);
> + else
> + priv->snor_timing0 |= TEGRA_GMI_ADV_WIDTH(1);
> +
> + if (!of_property_read_u32(child, "nvidia,snor-ce-width", &property))
> + priv->snor_timing0 |= TEGRA_GMI_CE_WIDTH(property);
> + else
> + priv->snor_timing0 |= TEGRA_GMI_CE_WIDTH(4);
> +
> + if (!of_property_read_u32(child, "nvidia,snor-we-width", &property))
> + priv->snor_timing1 |= TEGRA_GMI_WE_WIDTH(property);
> + else
> + priv->snor_timing1 |= TEGRA_GMI_WE_WIDTH(1);
> +
> + if (!of_property_read_u32(child, "nvidia,snor-oe-width", &property))
> + priv->snor_timing1 |= TEGRA_GMI_OE_WIDTH(property);
> + else
> + priv->snor_timing1 |= TEGRA_GMI_OE_WIDTH(1);
> +
> + if (!of_property_read_u32(child, "nvidia,snor-wait-width", &property))
> + priv->snor_timing1 |= TEGRA_GMI_WAIT_WIDTH(property);
> + else
> + priv->snor_timing1 |= TEGRA_GMI_WAIT_WIDTH(3);
> +
> +error_cs_decode:
> + if (ret < 0)
> + dev_err(dev, "failed to decode chip-select number\n");

Nit do we need another error message here? Can we add the "failed to
decode CS" part the earlier message?

> +
> + of_node_put(child);
> + return ret;
> +}
> +
> +static int tegra_gmi_probe(struct platform_device *pdev)
> +{
> + struct resource *res;
> + struct device *dev = &pdev->dev;
> + struct tegra_gmi_priv *priv;
> + int ret;
> +
> + priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
> + if (!priv)
> + return -ENOMEM;
> +
> + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> + priv->base = devm_ioremap_resource(dev, res);
> + if (IS_ERR(priv->base))
> + return PTR_ERR(priv->base);
> +
> + priv->clk = devm_clk_get(dev, "gmi");
> + if (IS_ERR(priv->clk)) {
> + dev_err(dev, "can not get clock\n");
> + return PTR_ERR(priv->clk);
> + }
> +
> + priv->rst = devm_reset_control_get(dev, "gmi");
> + if (IS_ERR(priv->rst)) {
> + dev_err(dev, "can not get reset\n");
> + return PTR_ERR(priv->rst);
> + }
> +
> + ret = tegra_gmi_parse_dt(dev, priv);
> + if (ret)
> + return ret;
> +
> + ret = clk_prepare_enable(priv->clk);
> + if (ret) {
> + dev_err(dev, "fail to enable clock.\n");
> + return ret;
> + }
> +
> + reset_control_assert(priv->rst);
> + udelay(2);
> + reset_control_deassert(priv->rst);
> +
> + tegra_gmi_init(dev, priv);
> +
> + ret = of_platform_default_populate(dev->of_node, NULL, dev);
> + if (ret < 0) {
> + dev_err(dev, "fail to create devices.\n");
> + tegra_gmi_disable(priv);
> + return ret;
> + }
> +
> + dev_set_drvdata(dev, priv);
> +
> + return 0;
> +}
> +
> +static int tegra_gmi_remove(struct platform_device *pdev)
> +{
> + struct tegra_gmi_priv *priv = dev_get_drvdata(&pdev->dev);
> +
> + of_platform_depopulate(&pdev->dev);
> +
> + tegra_gmi_disable(priv);
> +
> + return 0;
> +}
> +
> +static const struct of_device_id tegra_gmi_id_table[] = {
> + { .compatible = "nvidia,tegra20-gmi", },
> + { .compatible = "nvidia,tegra30-gmi", },
> + { }
> +};
> +MODULE_DEVICE_TABLE(of, tegra_gmi_id_table);
> +
> +static struct platform_driver tegra_gmi_driver = {
> + .probe = tegra_gmi_probe,
> + .remove = tegra_gmi_remove,
> + .driver = {
> + .name = "tegra-gmi",
> + .of_match_table = tegra_gmi_id_table,
> + },
> +};
> +module_platform_driver(tegra_gmi_driver);
> +
> +MODULE_AUTHOR("Mirza Krak <mirza.krak@gmail.com");
> +MODULE_DESCRIPTION("NVIDIA Tegra GMI Bus Driver");
> +MODULE_LICENSE("GPL v2");
> --
> 2.1.4
>

Cheers
Jon

--
nvpublic

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