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SubjectRe: [RFC 5/5] tty: Update hypervisor tty drivers to use core stdout parsing code.
Hi,

On Fri, Mar 28, 2014 at 09:08:05AM -0700, Grant Likely wrote:
> The evh_bytechan, hvc_opal and hvc_vio drivers all open code the parsing
> of the stdout node in the device tree. This patch simplifies the driver
> by removing the duplicated functionality.
>
> Signed-off-by: Grant Likely <grant.likely@linaro.org>
> ---
> drivers/of/base.c | 5 ++++-
> drivers/tty/ehv_bytechan.c | 43 ++++---------------------------------------
> drivers/tty/hvc/hvc_opal.c | 14 +++-----------
> drivers/tty/hvc/hvc_vio.c | 29 ++++++++++-------------------
> include/linux/of.h | 1 +
> 5 files changed, 22 insertions(+), 70 deletions(-)
>
> diff --git a/drivers/of/base.c b/drivers/of/base.c
> index a5643badeb1d..f845fd05d750 100644
> --- a/drivers/of/base.c
> +++ b/drivers/of/base.c
> @@ -35,7 +35,7 @@ struct device_node *of_allnodes;
> EXPORT_SYMBOL(of_allnodes);
> struct device_node *of_chosen;
> struct device_node *of_aliases;
> -static struct device_node *of_stdout;
> +struct device_node *of_stdout;
>
> static struct kset *of_kset;
>
> @@ -1956,9 +1956,12 @@ void of_alias_scan(void * (*dt_alloc)(u64 size, u64 align))
> of_chosen = of_find_node_by_path("/chosen@0");
>
> if (of_chosen) {
> + /* linux,stdout-path and /aliases/stdout are for legacy compatibility */
> const char *name = of_get_property(of_chosen, "stdout-path", NULL);
> if (!name)
> name = of_get_property(of_chosen, "linux,stdout-path", NULL);
> + if (!name)
> + name = of_get_property(of_aliases, "stdout", NULL);
> if (name)
> of_stdout = of_find_node_by_path(name);
> }
> diff --git a/drivers/tty/ehv_bytechan.c b/drivers/tty/ehv_bytechan.c
> index 0419b69e270f..4f485e88f60c 100644
> --- a/drivers/tty/ehv_bytechan.c
> +++ b/drivers/tty/ehv_bytechan.c
> @@ -108,55 +108,23 @@ static void disable_tx_interrupt(struct ehv_bc_data *bc)
> *
> * The byte channel to be used for the console is specified via a "stdout"
> * property in the /chosen node.
> - *
> - * For compatible with legacy device trees, we also look for a "stdout" alias.
> */

Did you mean to remove this /aliases/stdout checking? Based on the comment it
seems that some older device trees / platforms might rely on it?

> static int find_console_handle(void)
> {
> - struct device_node *np, *np2;
> + struct device_node *np = of_stdout;
> const char *sprop = NULL;
> const uint32_t *iprop;
>
> - np = of_find_node_by_path("/chosen");
> - if (np)
> - sprop = of_get_property(np, "stdout-path", NULL);
> -
> - if (!np || !sprop) {
> - of_node_put(np);
> - np = of_find_node_by_name(NULL, "aliases");
> - if (np)
> - sprop = of_get_property(np, "stdout", NULL);
> - }
> -
> - if (!sprop) {
> - of_node_put(np);
> - return 0;
> - }
> -
> /* We don't care what the aliased node is actually called. We only
> * care if it's compatible with "epapr,hv-byte-channel", because that
> - * indicates that it's a byte channel node. We use a temporary
> - * variable, 'np2', because we can't release 'np' until we're done with
> - * 'sprop'.
> + * indicates that it's a byte channel node.
> */
> - np2 = of_find_node_by_path(sprop);
> - of_node_put(np);
> - np = np2;
> - if (!np) {
> - pr_warning("ehv-bc: stdout node '%s' does not exist\n", sprop);
> - return 0;
> - }
> -
> - /* Is it a byte channel? */
> - if (!of_device_is_compatible(np, "epapr,hv-byte-channel")) {
> - of_node_put(np);
> + if (!np || !of_device_is_compatible(np, "epapr,hv-byte-channel"))
> return 0;
> - }
>
> stdout_irq = irq_of_parse_and_map(np, 0);
> if (stdout_irq == NO_IRQ) {
> - pr_err("ehv-bc: no 'interrupts' property in %s node\n", sprop);
> - of_node_put(np);
> + pr_err("ehv-bc: no 'interrupts' property in %s node\n", np->full_name);
> return 0;
> }
>
> @@ -167,12 +135,9 @@ static int find_console_handle(void)
> if (!iprop) {
> pr_err("ehv-bc: no 'hv-handle' property in %s node\n",
> np->name);
> - of_node_put(np);
> return 0;
> }
> stdout_bc = be32_to_cpu(*iprop);
> -
> - of_node_put(np);
> return 1;
> }
>
> diff --git a/drivers/tty/hvc/hvc_opal.c b/drivers/tty/hvc/hvc_opal.c
> index b01659bd4f7c..0ec1a80dd6a2 100644
> --- a/drivers/tty/hvc/hvc_opal.c
> +++ b/drivers/tty/hvc/hvc_opal.c
> @@ -322,22 +322,14 @@ static void udbg_init_opal_common(void)
>
> void __init hvc_opal_init_early(void)
> {
> - struct device_node *stdout_node = NULL;
> + struct device_node *stdout_node = of_node_get(of_stdout);
> const __be32 *termno;
> const char *name = NULL;

Name is no longer used, should be removed.

> const struct hv_ops *ops;
> u32 index;
>
> - /* find the boot console from /chosen/stdout */
> - if (of_chosen)
> - name = of_get_property(of_chosen, "linux,stdout-path", NULL);
> - if (name) {
> - stdout_node = of_find_node_by_path(name);
> - if (!stdout_node) {
> - pr_err("hvc_opal: Failed to locate default console!\n");
> - return;
> - }
> - } else {
> + /* If the console wasn't in /chosen, try /ibm,opal */
> + if (!stdout_node) {
> struct device_node *opal, *np;
>
> /* Current OPAL takeover doesn't provide the stdout


-Olof


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