Re: [PATCHv9 1/3] mfd: altera: Add Altera SDRAM Controller

From: Lee Jones
Date: Thu Jul 31 2014 - 04:26:55 EST

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In reply to: tthayer: "[PATCHv9 1/3] mfd: altera: Add Altera SDRAM Controller"
Next in thread: Thor Thayer: "Re: [PATCHv9 1/3] mfd: altera: Add Altera SDRAM Controller"
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On Wed, 30 Jul 2014, tthayer@xxxxxxxxxxxxxxxxxxxxx wrote:

> From: Thor Thayer <tthayer@xxxxxxxxxxxxxxxxxxxxx>
>
> Add a simple MFD for the Altera SDRAM Controller.
>
> Signed-off-by: Alan Tull <atull@xxxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Thor Thayer <tthayer@xxxxxxxxxxxxxxxxxxxxx>
> ---
> v1-8: The MFD implementation was not included in the original series.
>
> v9: New MFD implementation.
> ---
> MAINTAINERS | 5 ++
> drivers/mfd/Kconfig | 7 ++
> drivers/mfd/Makefile | 1 +
> drivers/mfd/altera-sdr.c | 162 ++++++++++++++++++++++++++++++++++++++++
> include/linux/mfd/altera-sdr.h | 102 +++++++++++++++++++++++++
> 5 files changed, 277 insertions(+)
> create mode 100644 drivers/mfd/altera-sdr.c
> create mode 100644 include/linux/mfd/altera-sdr.h
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 86efa7e..48a8923 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -1340,6 +1340,11 @@ M: Dinh Nguyen <dinguyen@xxxxxxxxxx>
> S: Maintained
> F: drivers/clk/socfpga/
>
> +ARM/SOCFPGA SDRAM CONTROLLER SUPPORT
> +M: Thor Thayer <tthayer@xxxxxxxxxx>
> +S: Maintained
> +F: drivers/mfd/altera-sdr.c
> +
> ARM/STI ARCHITECTURE
> M: Srinivas Kandagatla <srinivas.kandagatla@xxxxxxxxx>
> M: Maxime Coquelin <maxime.coquelin@xxxxxx>

This should be in a separate patch.

> diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
> index 6cc4b6a..8ce4961 100644
> --- a/drivers/mfd/Kconfig
> +++ b/drivers/mfd/Kconfig
> @@ -719,6 +719,13 @@ config MFD_STMPE
> Keypad: stmpe-keypad
> Touchscreen: stmpe-ts
>
> +config MFD_ALTERA_SDR
> + bool "Altera SDRAM Controller MFD"
> + depends on ARCH_SOCFPGA
> + select MFD_CORE
> + help
> + Support for Altera SDRAM Controller (SDR) MFD.
> +
> menu "STMicroelectronics STMPE Interface Drivers"
> depends on MFD_STMPE
>
> diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
> index 8afedba..24cc2b7 100644
> --- a/drivers/mfd/Makefile
> +++ b/drivers/mfd/Makefile
> @@ -169,3 +169,4 @@ obj-$(CONFIG_MFD_AS3711) += as3711.o
> obj-$(CONFIG_MFD_AS3722) += as3722.o
> obj-$(CONFIG_MFD_STW481X) += stw481x.o
> obj-$(CONFIG_MFD_IPAQ_MICRO) += ipaq-micro.o
> +obj-$(CONFIG_MFD_ALTERA_SDR) += altera-sdr.o
> diff --git a/drivers/mfd/altera-sdr.c b/drivers/mfd/altera-sdr.c
> new file mode 100644
> index 0000000..b5c6646
> --- /dev/null
> +++ b/drivers/mfd/altera-sdr.c
> @@ -0,0 +1,162 @@
> +/*
> + * SDRAM Controller (SDR) MFD
> + *
> + * Copyright (C) 2014 Altera Corporation
> + *
> + * 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/>.

Can you use the shorter version of the licence?

> + */

'\n' here.

> +#include <linux/io.h>
> +#include <linux/kernel.h>
> +#include <linux/mfd/altera-sdr.h>
> +#include <linux/mfd/core.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +
> +static const struct mfd_cell altera_sdr_devs[] = {
> +#if defined(CONFIG_EDAC_ALTERA_MC)

No need to do this, as it will only be matched if the driver is
enabled. Please remove the #iffery.

> + {
> + .name = "altr_sdram_edac",
> + .of_compatible = "altr,sdram-edac",

What other devices will there be?

> + },
> +#endif
> +};
> +
> +u32 altera_sdr_readl(struct altera_sdr *sdr, u32 reg_offset)
> +{
> + return readl(sdr->reg_base + reg_offset);
> +}
> +EXPORT_SYMBOL_GPL(altera_sdr_readl);
> +
> +void altera_sdr_writel(struct altera_sdr *sdr, u32 reg_offset, u32 value)
> +{
> + writel(value, sdr->reg_base + reg_offset);
> +}
> +EXPORT_SYMBOL_GPL(altera_sdr_writel);

Why are you abstracting these?

Might be better to use Regmap even.

> +/* Get total memory size in bytes */
> +u32 altera_sdr_mem_size(struct altera_sdr *sdr)
> +{
> + u32 size;
> + u32 read_reg, row, bank, col, cs, width;

Weird that size is on its own. Either place on a single line or
separate them all.

> + read_reg = altera_sdr_readl(sdr, SDR_DRAMADDRW_OFST);
> + if (read_reg < 0)
> + return 0;
> +
> + width = altera_sdr_readl(sdr, SDR_DRAMIFWIDTH_OFST);
> + if (width < 0)
> + return 0;
> +
> + col = (read_reg & SDR_DRAMADDRW_COLBITS_MASK) >>
> + SDR_DRAMADDRW_COLBITS_LSB;
> + row = (read_reg & SDR_DRAMADDRW_ROWBITS_MASK) >>
> + SDR_DRAMADDRW_ROWBITS_LSB;
> + bank = (read_reg & SDR_DRAMADDRW_BANKBITS_MASK) >>
> + SDR_DRAMADDRW_BANKBITS_LSB;
> + cs = (read_reg & SDR_DRAMADDRW_CSBITS_MASK) >>
> + SDR_DRAMADDRW_CSBITS_LSB;

These would probably be better as macros.

> + /* Correct for ECC as its not addressible */
> + if (width == SDR_DRAMIFWIDTH_32B_ECC)
> + width = 32;
> + if (width == SDR_DRAMIFWIDTH_16B_ECC)
> + width = 16;
> +
> + /* calculate the SDRAM size base on this info */
> + size = 1 << (row + bank + col);
> + size = size * cs * (width / 8);
> + return size;
> +}
> +EXPORT_SYMBOL_GPL(altera_sdr_mem_size);

Should this really be done in here? Isn't this an SDRAM function?

> +static int altera_sdr_probe(struct platform_device *pdev)
> +{
> + struct device *dev = &pdev->dev;
> + struct altera_sdr *sdr;
> + struct resource *res;
> + void __iomem *base;
> + int ret;
> +
> + sdr = devm_kzalloc(dev, sizeof(*sdr), GFP_KERNEL);
> + if (!sdr)
> + return -ENOMEM;
> +
> + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> + if (!res)
> + return -ENOENT;
> +
> + base = devm_ioremap(dev, res->start, resource_size(res));

Instead use devm_ioremap_resource(), then you can omit the error
checking of platform_get_resource().

> + if (!base)
> + return -ENOMEM;
> +
> + sdr->dev = &pdev->dev;

Either use 'dev' here, or remove the top line in this function and use
&pdev->dev everywhere. I personally prefer the latter.

> + sdr->reg_base = base;
> +
> + ret = mfd_add_devices(sdr->dev, 0, altera_sdr_devs,
> + ARRAY_SIZE(altera_sdr_devs), NULL, 0, NULL);
> + if (ret)
> + dev_err(sdr->dev, "error adding devices");
> +
> + platform_set_drvdata(pdev, sdr);
> +
> + dev_dbg(dev, "Altera SDR MFD registered\n");
> +
> + return 0;
> +}
> +
> +static int altera_sdr_remove(struct platform_device *pdev)
> +{
> + struct altera_sdr *sdr = platform_get_drvdata(pdev);

No need for this, just use &pdev->dev.

> + mfd_remove_devices(sdr->dev);
> +
> + return 0;
> +}
> +
> +static const struct of_device_id of_altera_sdr_match[] = {
> + { .compatible = "altr,sdr", },
> + { },
> +};
> +
> +static const struct platform_device_id altera_sdr_ids[] = {
> + { "altera_sdr", },
> + { }
> +};

What's this for?

> +static struct platform_driver altera_sdr_driver = {
> + .driver = {
> + .name = "altera_sdr",
> + .owner = THIS_MODULE,

You can remove this line, it's taken care of for you.

> + .of_match_table = of_altera_sdr_match,
> + },
> + .probe = altera_sdr_probe,
> + .remove = altera_sdr_remove,
> + .id_table = altera_sdr_ids,
> +};
> +
> +static int __init altera_sdr_init(void)
> +{
> + return platform_driver_register(&altera_sdr_driver);
> +}
> +postcore_initcall(altera_sdr_init);

Why was this chosen?

> +static void __exit altera_sdr_exit(void)
> +{
> + platform_driver_unregister(&altera_sdr_driver);
> +}
> +module_exit(altera_sdr_exit);
> +
> +MODULE_AUTHOR("Alan Tull <atull@xxxxxxxxxx>");
> +MODULE_DESCRIPTION("Altera SDRAM Controller (SDR) MFD");
> +MODULE_LICENSE("GPL v2");
> diff --git a/include/linux/mfd/altera-sdr.h b/include/linux/mfd/altera-sdr.h
> new file mode 100644
> index 0000000..a5f5c39
> --- /dev/null
> +++ b/include/linux/mfd/altera-sdr.h
> @@ -0,0 +1,102 @@
> +/*
> + * Copyright (C) 2014 Altera Corporation
> + *
> + * 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/>.

Use the short version.

> + */

'\n' here.

> +#ifndef __LINUX_MFD_ALTERA_SDR_H
> +#define __LINUX_MFD_ALTERA_SDR_H
> +
> +/* SDRAM Controller register offsets */
> +#define SDR_CTLCFG_OFST 0x00
> +#define SDR_DRAMADDRW_OFST 0x2C
> +#define SDR_DRAMIFWIDTH_OFST 0x30
> +#define SDR_DRAMSTS_OFST 0x38
> +#define SDR_DRAMINTR_OFST 0x3C
> +#define SDR_SBECOUNT_OFST 0x40
> +#define SDR_DBECOUNT_OFST 0x44
> +#define SDR_ERRADDR_OFST 0x48
> +#define SDR_DROPCOUNT_OFST 0x4C
> +#define SDR_DROPADDR_OFST 0x50
> +#define SDR_CTRLGRP_LOWPWREQ_OFST 0x54
> +#define SDR_CTRLGRP_LOWPWRACK_OFST 0x58
> +
> +/* SDRAM Controller CtrlCfg Register Bit Masks */
> +#define SDR_CTLCFG_ECC_EN 0x400
> +#define SDR_CTLCFG_ECC_CORR_EN 0x800
> +#define SDR_CTLCFG_GEN_SB_ERR 0x2000
> +#define SDR_CTLCFG_GEN_DB_ERR 0x4000
> +
> +#define SDR_CTLCFG_ECC_AUTO_EN (SDR_CTLCFG_ECC_EN | \
> + SDR_CTLCFG_ECC_CORR_EN)
> +
> +/* SDRAM Controller Address Widths Field Register */
> +#define SDR_DRAMADDRW_COLBITS_MASK 0x001F
> +#define SDR_DRAMADDRW_COLBITS_LSB 0
> +#define SDR_DRAMADDRW_ROWBITS_MASK 0x03E0
> +#define SDR_DRAMADDRW_ROWBITS_LSB 5
> +#define SDR_DRAMADDRW_BANKBITS_MASK 0x1C00
> +#define SDR_DRAMADDRW_BANKBITS_LSB 10
> +#define SDR_DRAMADDRW_CSBITS_MASK 0xE000
> +#define SDR_DRAMADDRW_CSBITS_LSB 13

We normally call _LSB, _SHIFT.

> +/* SDRAM Controller Interface Data Width Defines */
> +#define SDR_DRAMIFWIDTH_16B_ECC 24
> +#define SDR_DRAMIFWIDTH_32B_ECC 40
> +
> +/* SDRAM Controller DRAM Status Register Bit Masks */
> +#define SDR_DRAMSTS_SBEERR 0x04
> +#define SDR_DRAMSTS_DBEERR 0x08
> +#define SDR_DRAMSTS_CORR_DROP 0x10
> +
> +/* SDRAM Controller DRAM IRQ Register Bit Masks */
> +#define SDR_DRAMINTR_INTREN 0x01
> +#define SDR_DRAMINTR_SBEMASK 0x02
> +#define SDR_DRAMINTR_DBEMASK 0x04
> +#define SDR_DRAMINTR_CORRDROPMASK 0x08
> +#define SDR_DRAMINTR_INTRCLR 0x10
> +
> +/* SDRAM Controller Single Bit Error Count Register Bit Masks */
> +#define SDR_SBECOUNT_COUNT_MASK 0x0F
> +
> +/* SDRAM Controller Double Bit Error Count Register Bit Masks */
> +#define SDR_DBECOUNT_COUNT_MASK 0x0F
> +
> +/* SDRAM Controller ECC Error Address Register Bit Masks */
> +#define SDR_ERRADDR_ADDR_MASK 0xFFFFFFFF
> +
> +/* SDRAM Controller ECC Autocorrect Drop Count Register Bit Masks */
> +#define SDR_DROPCOUNT_CORRMASK 0x0F
> +
> +/* SDRAM Controller ECC AutoCorrect Error Address Register Bit Masks */
> +#define SDR_DROPADDR_ADDR_MASK 0xFFFFFFFF
> +
> +#define SELFRSHREQ_POS 3
> +#define SELFRSHREQ_MASK 0x8
> +
> +#define SELFRFSHMASK_POS 4
> +#define SELFRFSHMASK_MASK 0x30
> +
> +#define SELFRFSHACK_POS 1
> +#define SELFRFSHACK_MASK 0x2
> +
> +struct altera_sdr {
> + struct device *dev;
> + void __iomem *reg_base;
> +};
> +
> +/* Register access API */
> +u32 altera_sdr_readl(struct altera_sdr *sdr, u32 reg_offset);
> +void altera_sdr_writel(struct altera_sdr *sdr, u32 reg_offset, u32 value);

Regmap?

> +u32 altera_sdr_mem_size(struct altera_sdr *sdr);
> +
> +#endif /* __LINUX_MFD_ALTERA_SDR_H */

--
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org â Open source software for ARM SoCs
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In reply to: tthayer: "[PATCHv9 1/3] mfd: altera: Add Altera SDRAM Controller"
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