[RFC,2/2] ARM: vf610: Add SoC bus support for Vybrid

Implements SoC bus support to export SoC specific information. Read
the unique SoC ID from the Vybrid On Chip One Time Programmable (OCOTP)
controller, SoC specific information from the Miscellaneous System
Control Module (MSCM), revision from the ROM revision register and
expose it via the SoC bus infrastructure.

Signed-off-by: Sanchayan Maity <maitysanchayan@gmail.com>
---
 arch/arm/mach-imx/mach-vf610.c | 76 +++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 75 insertions(+), 1 deletion(-)

Hi Sanchayan,

The implementation looks good from my perspective. While the output
differs a bit from what i.MX6 provides, I think its closer to what is
specified. Also I like that we have the ROM revision available, since
this information is relevant to identify early versions of the chip
which have had issues...

Some minor things below.

On 2015-05-11 07:11, Sanchayan Maity wrote:
> Implements SoC bus support to export SoC specific information. Read
> the unique SoC ID from the Vybrid On Chip One Time Programmable (OCOTP)
> controller, SoC specific information from the Miscellaneous System
> Control Module (MSCM), revision from the ROM revision register and
> expose it via the SoC bus infrastructure.
> 
> Signed-off-by: Sanchayan Maity <maitysanchayan@gmail.com>
> ---
>  arch/arm/mach-imx/mach-vf610.c | 76 +++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 75 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/arm/mach-imx/mach-vf610.c b/arch/arm/mach-imx/mach-vf610.c
> index 1ba7738..74681f1 100644
> --- a/arch/arm/mach-imx/mach-vf610.c
> +++ b/arch/arm/mach-imx/mach-vf610.c
> @@ -9,13 +9,87 @@
>  
>  #include <linux/of_platform.h>
>  #include <linux/irqchip.h>
> +#include <linux/slab.h>
> +#include <linux/sys_soc.h>
> +#include <linux/mfd/syscon.h>
> +#include <linux/regmap.h>
> +#include <linux/random.h>
> +#include <linux/io.h>
>  #include <asm/mach/arch.h>
>  #include <asm/hardware/cache-l2x0.h>
>  #include "common.h"
>  
> +#define OCOTP_CFG0_OFFSET      0x00000410
> +#define OCOTP_CFG1_OFFSET      0x00000420
> +#define MSCM_CPxCOUNT_OFFSET   0x0000002C
> +#define MSCM_CPxCFG1_OFFSET    0x00000014
> +#define ROM_REVISION_REGISTER  0x00000080
> +
>  static void __init vf610_init_machine(void)
>  {
> -	of_platform_populate(NULL, of_default_bus_match_table, NULL, NULL);
> +	struct regmap *ocotp_regmap, *mscm_regmap;
> +	struct soc_device_attribute *soc_dev_attr;
> +	struct device *parent = NULL;
> +	struct soc_device *soc_dev;
> +	char soc_type[] = "xx0";
> +	void __iomem *rom_rev;
> +	u32 cpxcount, cpxcfg1;
> +	u32 soc_id1, soc_id2;
> +	u64 soc_id;
> +
> +	ocotp_regmap = syscon_regmap_lookup_by_compatible("fsl,vf610-ocotp");
> +	if (IS_ERR(ocotp_regmap)) {
> +		pr_err("regmap lookup for octop failed\n");
> +		goto out;
> +	}
> +
> +	mscm_regmap = syscon_regmap_lookup_by_compatible("fsl,vf610-mscm-cpucfg");
> +	if (IS_ERR(mscm_regmap)) {
> +		pr_err("regmap lookup for mscm failed");
> +		goto out;
> +	}
> +
> +	regmap_read(ocotp_regmap, OCOTP_CFG0_OFFSET, &soc_id1);
> +	regmap_read(ocotp_regmap, OCOTP_CFG1_OFFSET, &soc_id2);
> +
> +	soc_id = (u64) soc_id1 << 32 | soc_id2;
> +	add_device_randomness(&soc_id, sizeof(soc_id));
> +
> +	regmap_read(mscm_regmap, MSCM_CPxCOUNT_OFFSET, &cpxcount);
> +	regmap_read(mscm_regmap, MSCM_CPxCFG1_OFFSET, &cpxcfg1);
> +
> +	soc_type[0] = cpxcount ? '6' : '5'; /* Dual Core => VF6x0 */
> +	soc_type[1] = cpxcfg1 ? '1' : '0'; /* L2 Cache => VFx10 */
> +
> +	soc_dev_attr = kzalloc(sizeof(*soc_dev_attr), GFP_KERNEL);
> +	if (!soc_dev_attr)
> +		goto out;

This out seems not to take care of the memory allocated just above.

> +
> +	soc_dev_attr->machine = kasprintf(GFP_KERNEL, "Freescale Vybrid");
> +	soc_dev_attr->soc_id = kasprintf(GFP_KERNEL, "%llx", soc_id);

I would prefer %016llx as format, that shows that we have 64 bit
identifier even when the highest bit is 0.

> +	soc_dev_attr->family = kasprintf(GFP_KERNEL, "Freescale Vybrid VF%s",
> +								 soc_type);
> +
> +	rom_rev = ioremap(ROM_REVISION_REGISTER, SZ_1);
> +	if (rom_rev)
> +		soc_dev_attr->revision = kasprintf(GFP_KERNEL, "%08x",
> +						readl(rom_rev));

We should add the ROM to the device tree too. The memory map documented
in the RM states that the ROM is accessable at 0x0000_0000-0x007fffff,
that would be 8MiB. However, according to the RM, the on-chip ROM is
only 96KiB. I quickly checked, U-Boot crashed when reading after
0x00018000, which is the 96KiB boundary, hence I would add a DT node
with compatible fsl,vf610-ocrom or something which has a register range
from 0x0-0x00017fff.

> +
> +	soc_dev = soc_device_register(soc_dev_attr);
> +	if (IS_ERR(soc_dev)) {
> +		if (!rom_rev)
> +			kfree(soc_dev_attr->revision);
> +		kfree(soc_dev_attr->family);
> +		kfree(soc_dev_attr->soc_id);
> +		kfree(soc_dev_attr->machine);
> +		kfree(soc_dev_attr);
> +		goto out;
> +	}
> +
> +	parent = soc_device_to_device(soc_dev);
> +
> +out:
> +	of_platform_populate(NULL, of_default_bus_match_table, NULL, parent);
>  	vf610_pm_init();
>  }