Thara Gopinath <thara@xxxxxx> writes:
> This patch introduces a user list of devices associated with each
> voltage domain instance. The user list is implemented using plist
> structure with priority node populated with the voltage values.
> This patch also adds an API which will take in a device and
> requested voltage as parameters, adds the info to the user list
> and returns back the maximum voltage requested by all the user
> devices. This can be used anytime to get the voltage that the
> voltage domain instance can be transitioned into.
>
> Signed-off-by: Thara Gopinath <thara@xxxxxx>
> ---
> arch/arm/mach-omap2/voltage.c | 94 +++++++++++++++++++++++++++++
> arch/arm/plat-omap/include/plat/voltage.h | 2 +
> 2 files changed, 96 insertions(+), 0 deletions(-)
>
> diff --git a/arch/arm/mach-omap2/voltage.c b/arch/arm/mach-omap2/voltage.c
> index 6a07fe9..4624250 100644
> --- a/arch/arm/mach-omap2/voltage.c
> +++ b/arch/arm/mach-omap2/voltage.c
> @@ -24,6 +24,9 @@
> #include <linux/clk.h>
> #include <linux/err.h>
> #include <linux/debugfs.h>
> +#include <linux/spinlock.h>
> +#include <linux/plist.h>
> +#include <linux/slab.h>
>
> #include <plat/omap-pm.h>
> #include <plat/omap34xx.h>
> @@ -95,6 +98,20 @@ struct vp_reg_val {
> };
>
> /**
> + * omap_vdd_user_list - The per vdd user list
> + *
> + * @dev : The device asking for the vdd to be set at a particular
> + * voltage
> + * @node : The list head entry
> + * @volt : The voltage requested by the device <dev>
> + */
> +struct omap_vdd_user_list {
> + struct device *dev;
> + struct plist_node node;
> + u32 volt;
> +};
> +
> +/**
> * omap_vdd_info - Per Voltage Domain info
> *
> * @volt_data : voltage table having the distinct voltages supported
> @@ -105,6 +122,9 @@ struct vp_reg_val {
> * vp registers
> * @volt_clk : the clock associated with the vdd.
> * @opp_dev : the 'struct device' associated with this vdd.
> + * @user_lock : the lock to be used by the plist user_list
> + * @user_list : the list head maintaining the various users
> + * of this vdd with the voltage requested by each user.
> * @volt_data_count : Number of distinct voltages supported by this vdd.
> * @nominal_volt : Nominal voltaged for this vdd.
> * cmdval_reg : Voltage controller cmdval register.
> @@ -117,6 +137,9 @@ struct omap_vdd_info{
> struct clk *volt_clk;
> struct device *opp_dev;
> struct voltagedomain voltdm;
> + spinlock_t user_lock;
> + struct plist_head user_list;
> + struct mutex scaling_mutex;
> int volt_data_count;
> unsigned long nominal_volt;
> u8 cmdval_reg;
> @@ -785,11 +808,18 @@ static void __init vdd_data_configure(struct omap_vdd_info *vdd)
> struct dentry *vdd_debug;
> char name[16];
> #endif
> +
> if (cpu_is_omap34xx())
> omap3_vdd_data_configure(vdd);
> else if (cpu_is_omap44xx())
> omap4_vdd_data_configure(vdd);
>
> + /* Init the plist */
> + spin_lock_init(&vdd->user_lock);
> + plist_head_init(&vdd->user_list, &vdd->user_lock);
> + /* Init the DVFS mutex */
> + mutex_init(&vdd->scaling_mutex);
> +
> #ifdef CONFIG_PM_DEBUG
> strcpy(name, "vdd_");
> strcat(name, vdd->voltdm.name);
> @@ -1142,6 +1172,70 @@ unsigned long omap_vp_get_curr_volt(struct voltagedomain *voltdm)
> }
>
> /**
> + * omap_voltage_add_userreq : API to keep track of various requests to
> + * scale the VDD and returns the best possible
> + * voltage the VDD can be put to.
> + * @volt_domain: pointer to the voltage domain.
> + * @dev : the device pointer.
> + * @volt : the voltage which is requested by the device.
> + *
> + * This API is to be called before the actual voltage scaling is
> + * done to determine what is the best possible voltage the VDD can
> + * be put to. This API adds the device <dev> in the user list of the
> + * vdd <volt_domain> with <volt> as the requested voltage. The user list
> + * is a plist with the priority element absolute voltage values.
> + * The API then finds the maximum of all the requested voltages for
> + * the VDD and returns it back through <volt> pointer itself.
> + * Returns error value in case of any errors.
> + */
> +int omap_voltage_add_userreq(struct voltagedomain *voltdm, struct device *dev,
> + unsigned long *volt)
How about just omap_voltage_add_request()
Also, do we need both voltdm and dev? With your other patches, can't we
look up the voltm based on dev? Or, is there a need for a device to add
a request in a voltage domain other than the one to which it belongs?
Also, how does one remove a voltage request?
> +{
> + struct omap_vdd_info *vdd;
> + struct omap_vdd_user_list *user;
> + struct plist_node *node;
> + int found = 0;
> +
> + if (!voltdm || IS_ERR(voltdm)) {
> + pr_warning("%s: VDD specified does not exist!\n", __func__);
> + return -EINVAL;
> + }
> +
> + vdd = container_of(voltdm, struct omap_vdd_info, voltdm);
> +
> + mutex_lock(&vdd->scaling_mutex);
> +
> + plist_for_each_entry(user, &vdd->user_list, node) {
> + if (user->dev == dev) {
> + found = 1;
> + break;
> + }
> + }
Minor: I'm not crazy about the 'found' flag. IMO, readability is
improved if you init 'user = NULL' above, use a tmp pointer to
walk the list, and rather than 'found = 1', do 'user = tmp_user'
when you find the match.
> +
> + if (!found) {
and here, do if (!user)
> + user = kzalloc(sizeof(struct omap_vdd_user_list), GFP_KERNEL);
> + if (!user) {
> + pr_err("%s: Unable to creat a new user for vdd_%s\n",
> + __func__, voltdm->name);
> + mutex_unlock(&vdd->scaling_mutex);
> + return -ENOMEM;
> + }
> + user->dev = dev;
> + } else {
> + plist_del(&user->node, &vdd->user_list);
hmm... if we get here, we didn't find a match, so 'user' points to the
last element in the list (which is the highest voltage request, I
guess), or even NULL if the list is empty. Then, this node is deleted.
-ECONFUSED
> + }
> +
> + plist_node_init(&user->node, *volt);
> + plist_add(&user->node, &vdd->user_list);
> + node = plist_first(&vdd->user_list);
> + *volt = node->prio;
> +
> + mutex_unlock(&vdd->scaling_mutex);
> +
> + return 0;
> +}
Can't think of a use-case now (cuz it's Friday), but would we ever want
to add multiple requests per device?
The current approch will only track one request per device.
Kevin
> +/**
> * omap_vp_enable : API to enable a particular VP
> * @voltdm: pointer to the VDD whose VP is to be enabled.
> *
> diff --git a/arch/arm/plat-omap/include/plat/voltage.h b/arch/arm/plat-omap/include/plat/voltage.h
> index 3e8cf03..fffd086 100644
> --- a/arch/arm/plat-omap/include/plat/voltage.h
> +++ b/arch/arm/plat-omap/include/plat/voltage.h
> @@ -144,6 +144,8 @@ struct omap_volt_data *omap_voltage_get_voltdata(struct voltagedomain *voltdm,
> unsigned long volt);
> void omap_voltage_register_pmic(struct omap_volt_pmic_info *pmic_info);
> unsigned long omap_voltage_get_nom_volt(struct voltagedomain *voltdm);
> +int omap_voltage_add_userreq(struct voltagedomain *voltdm, struct device *dev,
> + unsigned long *volt);
> #ifdef CONFIG_PM
> void omap_voltage_init_vc(struct omap_volt_vc_data *setup_vc);
> void omap_change_voltscale_method(int voltscale_method);
--
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