diff options
Diffstat (limited to 'drivers/mailbox/pcc.c')
| -rw-r--r-- | drivers/mailbox/pcc.c | 122 |
1 files changed, 37 insertions, 85 deletions
diff --git a/drivers/mailbox/pcc.c b/drivers/mailbox/pcc.c index 977c814cdf6f..7e91d68a3ac3 100644 --- a/drivers/mailbox/pcc.c +++ b/drivers/mailbox/pcc.c @@ -20,10 +20,35 @@ * shared memory regions as defined in the PCC table entries. The PCC * specification supports a Doorbell mechanism for the PCC clients * to notify the platform about new data. This Doorbell information - * is also specified in each PCC table entry. See pcc_send_data() - * and pcc_tx_done() for basic mode of operation. + * is also specified in each PCC table entry. * - * For more details about PCC, please see the ACPI specification from + * Typical high level flow of operation is: + * + * PCC Reads: + * * Client tries to acquire a channel lock. + * * After it is acquired it writes READ cmd in communication region cmd + * address. + * * Client issues mbox_send_message() which rings the PCC doorbell + * for its PCC channel. + * * If command completes, then client has control over channel and + * it can proceed with its reads. + * * Client releases lock. + * + * PCC Writes: + * * Client tries to acquire channel lock. + * * Client writes to its communication region after it acquires a + * channel lock. + * * Client writes WRITE cmd in communication region cmd address. + * * Client issues mbox_send_message() which rings the PCC doorbell + * for its PCC channel. + * * If command completes, then writes have succeded and it can release + * the channel lock. + * + * There is a Nominal latency defined for each channel which indicates + * how long to wait until a command completes. If command is not complete + * the client needs to retry or assume failure. + * + * For more details about PCC, please see the ACPI specification from * http://www.uefi.org/ACPIv5.1 Section 14. * * This file implements PCC as a Mailbox controller and allows for PCC @@ -42,8 +67,6 @@ #include "mailbox.h" #define MAX_PCC_SUBSPACES 256 -#define PCCS_SS_SIG_MAGIC 0x50434300 -#define PCC_CMD_COMPLETE 0x1 static struct mbox_chan *pcc_mbox_channels; @@ -71,23 +94,6 @@ static struct mbox_chan *get_pcc_channel(int id) } /** - * get_subspace_id - Given a Mailbox channel, find out the - * PCC subspace id. - * @chan: Pointer to Mailbox Channel from which we want - * the index. - * Return: Errno if not found, else positive index number. - */ -static int get_subspace_id(struct mbox_chan *chan) -{ - unsigned int id = chan - pcc_mbox_channels; - - if (id < 0 || id > pcc_mbox_ctrl.num_chans) - return -ENOENT; - - return id; -} - -/** * pcc_mbox_request_channel - PCC clients call this function to * request a pointer to their PCC subspace, from which they * can get the details of communicating with the remote. @@ -117,7 +123,7 @@ struct mbox_chan *pcc_mbox_request_channel(struct mbox_client *cl, chan = get_pcc_channel(subspace_id); if (!chan || chan->cl) { - dev_err(dev, "%s: PCC mailbox not free\n", __func__); + dev_err(dev, "Channel not found for idx: %d\n", subspace_id); return ERR_PTR(-EBUSY); } @@ -161,81 +167,30 @@ void pcc_mbox_free_channel(struct mbox_chan *chan) EXPORT_SYMBOL_GPL(pcc_mbox_free_channel); /** - * pcc_tx_done - Callback from Mailbox controller code to - * check if PCC message transmission completed. - * @chan: Pointer to Mailbox channel on which previous - * transmission occurred. - * - * Return: TRUE if succeeded. - */ -static bool pcc_tx_done(struct mbox_chan *chan) -{ - struct acpi_pcct_hw_reduced *pcct_ss = chan->con_priv; - struct acpi_pcct_shared_memory *generic_comm_base = - (struct acpi_pcct_shared_memory *) pcct_ss->base_address; - u16 cmd_delay = pcct_ss->latency; - unsigned int retries = 0; - - /* Try a few times while waiting for platform to consume */ - while (!(readw_relaxed(&generic_comm_base->status) - & PCC_CMD_COMPLETE)) { - - if (retries++ < 5) - udelay(cmd_delay); - else { - /* - * If the remote is dead, this will cause the Mbox - * controller to timeout after mbox client.tx_tout - * msecs. - */ - pr_err("PCC platform did not respond.\n"); - return false; - } - } - return true; -} - -/** - * pcc_send_data - Called from Mailbox Controller code to finally - * transmit data over channel. + * pcc_send_data - Called from Mailbox Controller code. Used + * here only to ring the channel doorbell. The PCC client + * specific read/write is done in the client driver in + * order to maintain atomicity over PCC channel once + * OS has control over it. See above for flow of operations. * @chan: Pointer to Mailbox channel over which to send data. - * @data: Actual data to be written over channel. + * @data: Client specific data written over channel. Used here + * only for debug after PCC transaction completes. * * Return: Err if something failed else 0 for success. */ static int pcc_send_data(struct mbox_chan *chan, void *data) { struct acpi_pcct_hw_reduced *pcct_ss = chan->con_priv; - struct acpi_pcct_shared_memory *generic_comm_base = - (struct acpi_pcct_shared_memory *) pcct_ss->base_address; struct acpi_generic_address doorbell; u64 doorbell_preserve; u64 doorbell_val; u64 doorbell_write; - u16 cmd = *(u16 *) data; - u16 ss_idx = -1; - - ss_idx = get_subspace_id(chan); - - if (ss_idx < 0) { - pr_err("Invalid Subspace ID from PCC client\n"); - return -EINVAL; - } doorbell = pcct_ss->doorbell_register; doorbell_preserve = pcct_ss->preserve_mask; doorbell_write = pcct_ss->write_mask; - /* Write to the shared comm region. */ - writew(cmd, &generic_comm_base->command); - - /* Write Subspace MAGIC value so platform can identify destination. */ - writel((PCCS_SS_SIG_MAGIC | ss_idx), &generic_comm_base->signature); - - /* Flip CMD COMPLETE bit */ - writew(0, &generic_comm_base->status); - - /* Sync notification from OSPM to Platform. */ + /* Sync notification from OS to Platform. */ acpi_read(&doorbell_val, &doorbell); acpi_write((doorbell_val & doorbell_preserve) | doorbell_write, &doorbell); @@ -245,7 +200,6 @@ static int pcc_send_data(struct mbox_chan *chan, void *data) static struct mbox_chan_ops pcc_chan_ops = { .send_data = pcc_send_data, - .last_tx_done = pcc_tx_done, }; /** @@ -351,8 +305,6 @@ static int pcc_mbox_probe(struct platform_device *pdev) pcc_mbox_ctrl.chans = pcc_mbox_channels; pcc_mbox_ctrl.ops = &pcc_chan_ops; - pcc_mbox_ctrl.txdone_poll = true; - pcc_mbox_ctrl.txpoll_period = 10; pcc_mbox_ctrl.dev = &pdev->dev; pr_info("Registering PCC driver as Mailbox controller\n"); |