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Message-ID: <20170127081712.x2hprtpo2aolungc@lukather>
Date: Fri, 27 Jan 2017 09:17:12 +0100
From: Maxime Ripard <maxime.ripard@...e-electrons.com>
To: Icenowy Zheng <icenowy@...c.xyz>
Cc: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
Rob Herring <robh+dt@...nel.org>, Chen-Yu Tsai <wens@...e.org>,
devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
linux-kernel@...r.kernel.org, linux-sunxi@...glegroups.com
Subject: Re: [PATCH 1/2] nvmem: sunxi-sid: add support for H3 and A64's SID
controller
Hi,
On Thu, Jan 26, 2017 at 07:33:44PM +0800, Icenowy Zheng wrote:
> H3 and A64 SoCs have a bigger SID controller, which has its direct read
> address at 0x200 position in the SID block, not 0x0.
>
> Also, H3 SID controller has some silicon bug that makes the direct read
> value wrong at first, add code to workaround the bug. (This bug has
> already been fixed on A64 and later SoCs)
>
> Signed-off-by: Icenowy Zheng <icenowy@...c.xyz>
> ---
> .../bindings/nvmem/allwinner,sunxi-sid.txt | 22 +++-
> drivers/nvmem/sunxi_sid.c | 112 +++++++++++++++++++--
> 2 files changed, 123 insertions(+), 11 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/nvmem/allwinner,sunxi-sid.txt b/Documentation/devicetree/bindings/nvmem/allwinner,sunxi-sid.txt
> index d543ed3f5363..d7400c415338 100644
> --- a/Documentation/devicetree/bindings/nvmem/allwinner,sunxi-sid.txt
> +++ b/Documentation/devicetree/bindings/nvmem/allwinner,sunxi-sid.txt
> @@ -1,8 +1,16 @@
> Allwinner sunxi-sid
>
> Required properties:
> -- compatible: "allwinner,sun4i-a10-sid" or "allwinner,sun7i-a20-sid"
> -- reg: Should contain registers location and length
> +- compatible: Should be one of the following (depending on your SoC):
> + "allwinner,sun4i-a10-sid"
> + "allwinner,sun7i-a20-sid"
> + "allwinner,sun8i-h3-sid"
> + "allwinner,sun50i-a64-sid"
> +
> +- reg: Should contain registers location and registers length, for A10 and A20
> + SoCs the length is directly the length of SID; for H3, A64 and newer SoCs
> + the length should be the sum of the length of SID and the offset of the value
> + (0x200).
>
> = Data cells =
> Are child nodes of qfprom, bindings of which as described in
> @@ -19,3 +27,13 @@ Example for sun7i:
> compatible = "allwinner,sun7i-a20-sid";
> reg = <0x01c23800 0x200>
> };
> +
> +Example for sun8i-h3:
> + sid@...14000 {
> + compatible = "allwinner,sun8i-h3-sid";
> + /*
> + * The length of SID on H3 is 0x100 bytes, add the value offset
> + * 0x200, so the total length should be 0x300.
> + */
> + reg = <0x01c14000 0x300>;
No, it should be the size of the memory region used and documented for
that device, ie 1kB (0x400) in the H3 case, just like any other reg
property.
> + };
> diff --git a/drivers/nvmem/sunxi_sid.c b/drivers/nvmem/sunxi_sid.c
> index 1567ccca8de3..2e327a66a938 100644
> --- a/drivers/nvmem/sunxi_sid.c
> +++ b/drivers/nvmem/sunxi_sid.c
> @@ -20,10 +20,28 @@
> #include <linux/module.h>
> #include <linux/nvmem-provider.h>
> #include <linux/of.h>
> +#include <linux/of_device.h>
> #include <linux/platform_device.h>
> #include <linux/slab.h>
> #include <linux/random.h>
>
> +/* Registers and special values for doing register-based SID readout on H3 */
> +#define SUN8I_SID_PRCTL 0x40
> +#define SUN8I_SID_RDKEY 0x60
> +
> +#define SUN8I_SID_OP_LOCK 0xAC
> +#define SUN8I_SID_OFFSET_MASK 0x1FF
> +#define SUN8I_SID_OFFSET_SHIFT 16
> +#define SUN8I_SID_LOCK_SHIFT 8
> +#define SUN8I_SID_READ BIT(1)
> +
> +/*
> + * For newer SoCs with a larger eFUSE, the bytes beyond the first 16 bytes are
> + * sparse, which makes it not suitable for adding randomness; legacy SoCs' SID
> + * have only 16 bytes, so we choose to use at most 16 bytes to add randomness.
> + */
> +#define SUNXI_SID_MAX_RANDOMNESS_SIZE 16
> +
> static struct nvmem_config econfig = {
> .name = "sunxi-sid",
> .read_only = true,
> @@ -32,8 +50,14 @@ static struct nvmem_config econfig = {
> .owner = THIS_MODULE,
> };
>
> +struct sunxi_sid_cfg {
> + u32 value_offset;
> + bool need_register_readout;
> +};
> +
> struct sunxi_sid {
> void __iomem *base;
> + u32 value_offset;
> };
>
> /* We read the entire key, due to a 32 bit read alignment requirement. Since we
> @@ -46,7 +70,8 @@ static u8 sunxi_sid_read_byte(const struct sunxi_sid *sid,
> {
> u32 sid_key;
>
> - sid_key = ioread32be(sid->base + round_down(offset, 4));
> + sid_key = ioread32be(sid->base + sid->value_offset +
> + round_down(offset, 4));
> sid_key >>= (offset % 4) * 8;
>
> return sid_key; /* Only return the last byte */
> @@ -64,26 +89,77 @@ static int sunxi_sid_read(void *context, unsigned int offset,
> return 0;
> }
>
> +static int sun8i_sid_register_readout(const struct sunxi_sid *sid,
> + const unsigned int word,
> + u32 *out)
> +{
> + u32 reg_val;
> + unsigned long expire = jiffies + msecs_to_jiffies(250);
> +
> + /* Set word, lock access, and set read command */
> + reg_val = (word & SUN8I_SID_OFFSET_MASK)
> + << SUN8I_SID_OFFSET_SHIFT;
> + reg_val |= SUN8I_SID_OP_LOCK << SUN8I_SID_LOCK_SHIFT;
> + reg_val |= SUN8I_SID_READ;
> + writel(reg_val, sid->base + SUN8I_SID_PRCTL);
> +
> + do {
> + reg_val = readl(sid->base + SUN8I_SID_PRCTL);
> + } while (time_before(jiffies, expire) && (reg_val & SUN8I_SID_READ));
> +
> + if (reg_val & SUN8I_SID_READ)
> + return -EIO;
> +
> + if (out)
> + *out = readl(sid->base + SUN8I_SID_RDKEY);
> + writel(0, sid->base + SUN8I_SID_PRCTL);
> + return 0;
> +}
> +
> static int sunxi_sid_probe(struct platform_device *pdev)
> {
> struct device *dev = &pdev->dev;
> struct resource *res;
> struct nvmem_device *nvmem;
> struct sunxi_sid *sid;
> - int ret, i, size;
> + int ret, i, size, randomness_size;
> char *randomness;
> + const struct sunxi_sid_cfg *cfg;
>
> sid = devm_kzalloc(dev, sizeof(*sid), GFP_KERNEL);
> if (!sid)
> return -ENOMEM;
>
> + cfg = of_device_get_match_data(dev);
> + if (!cfg)
> + return -EINVAL;
> + sid->value_offset = cfg->value_offset;
> +
> res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> sid->base = devm_ioremap_resource(dev, res);
> if (IS_ERR(sid->base))
> return PTR_ERR(sid->base);
>
> - size = resource_size(res) - 1;
> - econfig.size = resource_size(res);
> + size = resource_size(res) - cfg->value_offset;
> +
> + if (cfg->need_register_readout) {
> + /*
> + * H3's SID controller have a bug that the value at 0x200
> + * offset is not the correct value when the hardware is reset.
> + * However, after doing a register-based read operation, the
> + * value become right.
> + * Do a full read operation here, but ignore its value
> + * (as it's more fast to read by direct MMIO value than
> + * with registers)
> + */
> + for (i = 0; i < (size >> 2); i++) {
> + ret = sun8i_sid_register_readout(sid, i, NULL);
> + if (ret)
> + return ret;
> + }
> + }
> +
> + econfig.size = size;
> econfig.dev = dev;
> econfig.reg_read = sunxi_sid_read;
> econfig.priv = sid;
> @@ -91,16 +167,17 @@ static int sunxi_sid_probe(struct platform_device *pdev)
> if (IS_ERR(nvmem))
> return PTR_ERR(nvmem);
>
> - randomness = kzalloc(sizeof(u8) * (size), GFP_KERNEL);
> + randomness_size = max(size, SUNXI_SID_MAX_RANDOMNESS_SIZE);
> + randomness = kzalloc(sizeof(u8) * (randomness_size), GFP_KERNEL);
Why is that change needed?
Thanks,
Maxime
--
Maxime Ripard, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com
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