Re: [RFC PATCH 6/7] i2c: of: mark a whole array of regs as reserved

Geert Uytterhoeven
2020-02-21T10:09:37Z

Hi Wolfram,

On Thu, Feb 20, 2020 at 6:26 PM Wolfram Sang
<wsa+renesas@sang-engineering.com> wrote:
> Back then, 'reg' properties in I2C DT bindings only contained one
> address and this address was assigned a device and, thus, blocked.
> Meanwhile, chips using multiple addresses are common and the 'reg'
> property can be an array described by 'reg-names'. This code enhances
> I2C DT parsing, so it will reserve all addresses described in an array.
> They will be bound to the 'dummy' driver as 'reserved' iff the first
> address can be assigned successfully. If that is not the case, the array
> is not further considered. If one later address of the array can not be
> assigned, it will be reported but we don't bail out. The driver has to
> decide if that address is critical or not.
>
> Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>

Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>

One comment below.

> --- a/drivers/i2c/i2c-core-of.c
> +++ b/drivers/i2c/i2c-core-of.c
> @@ -21,20 +21,12 @@
>
> #include "i2c-core.h"
>
> -int of_i2c_get_board_info(struct device_node *node, struct i2c_board_info *info)
> +static void of_i2c_decode_board_info(struct device_node *node, u32 addr,
> + bool first_addr, struct i2c_board_info *info)
> {
> - u32 addr;
> - int ret;
> -
> memset(info, 0, sizeof(*info));
>
> - ret = of_property_read_u32(node, "reg", &addr);
> - if (ret) {
> - pr_err("invalid reg on %pOF\n", node);
> - return ret;
> - }
> -
> - if (of_modalias_node(node, info->type, sizeof(info->type)) < 0)
> + if (!first_addr || of_modalias_node(node, info->type, sizeof(info->type)) < 0)
> strlcpy(info->type, I2C_RESERVED_DRV_NAME, sizeof(I2C_RESERVED_DRV_NAME));
>
> if (addr & I2C_TEN_BIT_ADDRESS) {
> @@ -51,11 +43,27 @@ int of_i2c_get_board_info(struct device_node *node, struct i2c_board_info *info)
> info->of_node = node;
> info->fwnode = of_fwnode_handle(node);
>
> - if (of_property_read_bool(node, "host-notify"))
> - info->flags |= I2C_CLIENT_HOST_NOTIFY;
> + if (first_addr) {
> + if (of_property_read_bool(node, "host-notify"))
> + info->flags |= I2C_CLIENT_HOST_NOTIFY;
> +
> + if (of_get_property(node, "wakeup-source", NULL))
> + info->flags |= I2C_CLIENT_WAKE;
> + }
> +}
> +
> +int of_i2c_get_board_info(struct device_node *node, struct i2c_board_info *info)
> +{
> + u32 addr;
> + int ret;
> +
> + ret = of_property_read_u32(node, "reg", &addr);

Perhaps the time is ripe to start considering #address-cells, instead
of assuming 1, here ...

> + if (ret) {
> + pr_err("invalid reg on %pOF\n", node);
> + return ret;
> + }
>
> - if (of_get_property(node, "wakeup-source", NULL))
> - info->flags |= I2C_CLIENT_WAKE;
> + of_i2c_decode_board_info(node, addr, true, info);
>
> return 0;
> }
> @@ -64,21 +72,33 @@ EXPORT_SYMBOL_GPL(of_i2c_get_board_info);
> static struct i2c_client *of_i2c_register_device(struct i2c_adapter *adap,
> struct device_node *node)
> {
> - struct i2c_client *client;
> + struct i2c_client *client, *first_client = ERR_PTR(-ENOENT);
> struct i2c_board_info info;
> - int ret;
> + bool first_reg = true;
> + struct property *prop;
> + const __be32 *cur;
> + u32 reg;
>
> pr_debug("register %pOF\n", node);
>
> - ret = of_i2c_get_board_info(node, &info);
> - if (ret)
> - return ERR_PTR(ret);
> + of_property_for_each_u32(node, "reg", prop, cur, reg) {

... and especially here, if this code can ever be reused for i3c, which uses 3.

> + of_i2c_decode_board_info(node, reg, first_reg, &info);
> +
> + client = i2c_new_client_device(adap, &info);
> + if (IS_ERR(client)) {
> + pr_err("failure registering addr 0x%02x for %pOF\n",
> + reg, node);
> + if (first_reg)
> + return client;
> + }
>
> - client = i2c_new_client_device(adap, &info);
> - if (IS_ERR(client))
> - pr_err("failure registering %pOF\n", node);
> + if (first_reg) {
> + first_client = client;
> + first_reg = false;
> + }
> + }
>
> - return client;
> + return first_client;
> }
>
> void of_i2c_register_devices(struct i2c_adapter *adap)

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds