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SubjectRe: [PATCH 1/1] arm64: X-Gene AHBC platform bus driver
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Hi Feng,

On 2013-09-27 02:19, Feng Kan wrote:
> This driver setup the AHBC for SPI and SD drivers to use.

That's a bit thin for a description. What is AHBC? How does it relate
to SPI and SD? How is it used?

> Signed-off-by: Feng Kan <fkan@apm.com>
>
> ---
> arch/arm64/boot/dts/apm-storm.dtsi | 6 +
> drivers/bus/Kconfig | 9 ++
> drivers/bus/Makefile | 2 +
> drivers/bus/xgene_ahbc.c | 193
> ++++++++++++++++++++++++++++++++++++
> 4 files changed, 210 insertions(+), 0 deletions(-)
> create mode 100644 drivers/bus/xgene_ahbc.c
>
> diff --git a/arch/arm64/boot/dts/apm-storm.dtsi
> b/arch/arm64/boot/dts/apm-storm.dtsi
> index d994806..b9477ec 100644
> --- a/arch/arm64/boot/dts/apm-storm.dtsi
> +++ b/arch/arm64/boot/dts/apm-storm.dtsi
> @@ -178,6 +178,12 @@
> };
> };
>
> + ahbc: ahbc@1f2a0000 {
> + device_type = "ahbc";
> + compatible = "apm,xgene-ahbc";
> + reg = <0x0 0x1f2a0000 0x0 0x80000>;
> + };

Where is the binding documentation for this?

> serial0: serial@1c020000 {
> device_type = "serial";
> compatible = "ns16550";
> diff --git a/drivers/bus/Kconfig b/drivers/bus/Kconfig
> index 1f70e84..6cc361c68 100644
> --- a/drivers/bus/Kconfig
> +++ b/drivers/bus/Kconfig
> @@ -42,4 +42,13 @@ config ARM_CCI
> help
> Driver supporting the CCI cache coherent interconnect for ARM
> platforms.
> +
> +config XGENE_AHBC
> + tristate "X-Gene SoC AHB Bus Driver"
> + depends on ARM64 && ARCH_XGENE
> + default y if ARCH_XGENE
> + help
> + X-Gene SoC AHB bus driver is required for SPI and
> + SDIO to function properly.
> +
> endmenu
> diff --git a/drivers/bus/Makefile b/drivers/bus/Makefile
> index 8947bdd..0c7a4ca 100644
> --- a/drivers/bus/Makefile
> +++ b/drivers/bus/Makefile
> @@ -10,3 +10,5 @@ obj-$(CONFIG_OMAP_OCP2SCP) += omap-ocp2scp.o
> obj-$(CONFIG_OMAP_INTERCONNECT) += omap_l3_smx.o omap_l3_noc.o
> # CCI cache coherent interconnect for ARM platforms
> obj-$(CONFIG_ARM_CCI) += arm-cci.o
> +
> +obj-$(CONFIG_XGENE_AHBC) += xgene_ahbc.o
> diff --git a/drivers/bus/xgene_ahbc.c b/drivers/bus/xgene_ahbc.c
> new file mode 100644
> index 0000000..9554bb4
> --- /dev/null
> +++ b/drivers/bus/xgene_ahbc.c
> @@ -0,0 +1,193 @@
> +/**
> + * AppliedMicro X-Gene AHBC Driver
> + *
> + * Copyright (c) 2013, Applied Micro Circuits Corporation
> + * Author: Loc Ho <lho@apm.com>
> + * Author: Feng Kan <fkan@apm.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, write to the Free Software
> + * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
> + * MA 02111-1307 USA
> + *
> + */
> +#include <linux/module.h>
> +#include <linux/io.h>
> +#include <linux/clk.h>
> +#include <linux/of_platform.h>
> +#include <linux/of_address.h>
> +#include <linux/delay.h>
> +#include <linux/memblock.h>
> +
> +#define AHBC_DRIVER_VER "0.1"
> +
> +#define AIM_8_SIZE_CTL_ADDR 0x00000104
> +#define AIM_8_AXI_LO_ADDR 0x00000108
> +#define AIM_8_AXI_HI_ADDR 0x0000010c
> +
> +#define ARSB_F8_WR(src) (((u32)(src)<<23) & 0x03800000)
> +#define AWSB_F8_WR(src) (((u32)(src)<<20) & 0x00700000)
> +#define AIM_AXI_ADDRESS_LO_8_WR(src) (((u32)(src)) & 0x000fffff)
> +
> +/* Global Base Address */
> +#define REGSPEC_AHBC_GLBL_DIAG_CSR_I_BASE_ADDR 0x01f2ad000ULL

Global base address? Why isn't this part of your DT binding? Or is it
always included in the reg property? In any case, nuke this #define.

> +#define REGSPEC_CFG_MEM_RAM_SHUTDOWN_ADDR 0x00000070
> +#define REGSPEC_BLOCK_MEM_RDY_ADDR 0x00000074
> +
> +static void xgene_ahb_write(void *base, u32 offset, u32 val)
> +{
> + if (base == NULL)
> + return;
> +
> + writel_relaxed(val, base + offset);
> +}
> +
> +static void xgene_ahbc_init_mem(struct platform_device *pdev)
> +{
> + void *ahbc_base = platform_get_drvdata(pdev);
> + u32 diag_offset = REGSPEC_AHBC_GLBL_DIAG_CSR_I_BASE_ADDR & 0xFFFF;

So diag_offset is always 0xd000?

> + void *diagcsr_base = ahbc_base + diag_offset;
> + int timeout;
> + u32 val;
> +
> + if (ahbc_base == NULL)
> + return;
> +
> + if (readl(diagcsr_base + REGSPEC_CFG_MEM_RAM_SHUTDOWN_ADDR) == 0)
> + return;
> +
> + dev_dbg(&pdev->dev, "AHBC clear memory shutdown\n");
> + writel(0x00, diagcsr_base + REGSPEC_CFG_MEM_RAM_SHUTDOWN_ADDR);
> + readl(diagcsr_base + REGSPEC_CFG_MEM_RAM_SHUTDOWN_ADDR);
> +
> + val = readl(diagcsr_base + REGSPEC_BLOCK_MEM_RDY_ADDR);
> + timeout = 5000;
> + while (val != 0xFFFFFFFF && timeout-- > 0) {
> + val = readl(diagcsr_base + REGSPEC_BLOCK_MEM_RDY_ADDR);
> + if (val != 0xFFFFFFFF)
> + udelay(1);
> + }
> + if (timeout <= 0)
> + dev_err(&pdev->dev, "AHBC failed to remove RAM out of reset\n");

In that case, why not report the error to the caller?

> +}
> +
> +static int xgene_ahbc_hw_init(struct platform_device *pdev)
> +{
> + void *ahbc_base = platform_get_drvdata(pdev);
> + phys_addr_t ddr_phy;
> +
> + /**
> + * Set AHBC AIM windows for 4GB regardless of DDR size. This
> + * must map to Kernel memory space.
> + */
> + ddr_phy = memblock_phys_mem_size();
> + dev_dbg(&pdev->dev, "Setup AHBC AIM windows DDR 0x%llX\n",
> ddr_phy);
> + xgene_ahb_write(ahbc_base, AIM_8_SIZE_CTL_ADDR, 0x00000000);
> + xgene_ahb_write(ahbc_base, AIM_8_AXI_LO_ADDR,
> + ARSB_F8_WR(1) | AWSB_F8_WR(1) |
> + AIM_AXI_ADDRESS_LO_8_WR((u32) ddr_phy));
> + xgene_ahb_write(ahbc_base, AIM_8_AXI_HI_ADDR,
> + (u32) ((ddr_phy >> 32) << 20));
> +
> + return 0;
> +}
> +
> +static int __init xgene_ahbc_probe(struct platform_device *pdev)
> +{
> + struct resource res;
> + int rc;
> + void *reg;
> +
> + rc = of_address_to_resource(pdev->dev.of_node, 0, &res);
> + if (rc != 0) {
> + dev_err(&pdev->dev, "invalid resource address\n");
> + return -ENODEV;
> + }
> + reg = ioremap(res.start, res.end - res.start + 1);
> + if (reg == NULL) {
> + dev_err(&pdev->dev, "can not map resource\n");
> + return -ENODEV;
> + }

Use of_iomap instead of dealing with resources yourself.

> +
> + platform_set_drvdata(pdev, reg);
> +
> + /* Initialize the hardware */
> + xgene_ahbc_init_mem(pdev);
> + xgene_ahbc_hw_init(pdev);
> +
> + dev_info(&pdev->dev, "AHBC driver v%s\n", AHBC_DRIVER_VER);
> + return 0;
> +}
> +
> +static int xgene_ahbc_remove(struct platform_device *pdev)
> +{
> + void *ahbc_base = platform_get_drvdata(pdev);
> +
> + iounmap(ahbc_base);
> + platform_set_drvdata(pdev, NULL);
> + return 0;
> +}
> +
> +#if defined(CONFIG_PM)
> +static int xgene_ahbc_suspend(struct platform_device *dev,
> pm_message_t state)
> +{
> + /* Nothing to do here */
> + return 0;
> +}
> +
> +static int xgene_ahbc_resume(struct platform_device *pdev)
> +{
> + /* Initialize the hardware */
> + xgene_ahbc_init_mem(pdev);
> + xgene_ahbc_hw_init(pdev);
> + return 0;
> +}
> +#endif
> +
> +static const struct of_device_id xgene_ahbc_match[] = {
> + {.compatible = "apm,xgene-ahbc",},
> + {},
> +};
> +
> +MODULE_DEVICE_TABLE(of, xgene_ahbc_match);
> +
> +static struct platform_driver ahbc_driver = {
> + .probe = xgene_ahbc_probe,
> + .remove = xgene_ahbc_remove,
> +#if defined(CONFIG_PM)
> + .suspend = xgene_ahbc_suspend,
> + .resume = xgene_ahbc_resume,
> +#endif

It would be nicer to define xgene_ahbc_{suspend,ersume} to NULL if
!CONFIG_PM.

> + .driver = {
> + .name = "xgene-ahbc",
> + .owner = THIS_MODULE,
> + .of_match_table = xgene_ahbc_match,
> + },
> +};
> +
> +static int __init xgene_ahbc_init(void)
> +{
> + return platform_driver_register(&ahbc_driver);
> +}
> +subsys_initcall(xgene_ahbc_init);
> +
> +static void __exit xgene_ahbc_exit(void)
> +{
> + platform_driver_unregister(&ahbc_driver);
> +}
> +module_exit(xgene_ahbc_exit);
> +
> +MODULE_AUTHOR("Loc Ho <lho@apm.com>");
> +MODULE_DESCRIPTION("X-Gene AHBC driver");
> +MODULE_LICENSE("GPL");

Cheers,

M.
--
Fast, cheap, reliable. Pick two.


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