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Commit ee176e29 authored by David Collins's avatar David Collins
Browse files

spmi: spmi-pmic-arb: add support for SPMI write corruption workaround 



Add support for an AHB bus workaround which can be used to avoid
possible SPMI write transaction corruption on some platforms
which utilize PMIC arbiter version 5.  The workaround consists
of performing dummy reads of a PMIC arbiter register reached
via the AHB bus immediately before each register write during
an SPMI write transaction.

Change-Id: I13c7535f9fe823f9a2e74263ee5d5b674e0c1fbc
Signed-off-by: default avatarDavid Collins <collinsd@codeaurora.org>
parent e13b7564

Documentation/devicetree/bindings/spmi/qcom,spmi-pmic-arb.txt

+5 −0
Original line number Diff line number Diff line
@@ -42,6 +42,11 @@ Required properties: 
    cell 4: interrupt flags indicating level-sense information, as defined in

            dt-bindings/interrupt-controller/irq.h



Optional properties:

- qcom,enable-ahb-bus-workaround : Boolean flag which indicates that the AHB bus

				   workaround sequence should be used for SPMI

				   write transactions to avoid corruption



Example V1 PMIC-Arbiter:



	spmi {

drivers/spmi/spmi-pmic-arb.c

+18 −0
Original line number Diff line number Diff line
@@ -59,6 +59,8 @@ 
#define SPMI_OWNERSHIP_TABLE_REG(N)	(0x0700 + (4 * (N)))

#define SPMI_OWNERSHIP_PERIPH2OWNER(X)	((X) & 0x7)



#define SPMI_PROTOCOL_IRQ_STATUS	0x6000



/* Channel Status fields */

enum pmic_arb_chnl_status {

	PMIC_ARB_STATUS_DONE	= BIT(0),
@@ -148,6 +150,8 @@ struct apid_data { 
 * @ver_ops:		version dependent operations.

 * @ppid_to_apid	in-memory copy of PPID -> channel (APID) mapping table.

 *			v2 only.

 * @ahb_bus_wa:		Use AHB bus workaround to avoid write transaction

 *			corruption on some PMIC arbiter v5 platforms.

 */

struct spmi_pmic_arb {

	void __iomem		*rd_base;
@@ -172,6 +176,7 @@ struct spmi_pmic_arb { 
	u16			*ppid_to_apid;

	u16			last_apid;

	struct apid_data	apid_data[PMIC_ARB_MAX_PERIPHS];

	bool			ahb_bus_wa;

};



/**
@@ -217,6 +222,16 @@ struct pmic_arb_ver_ops { 
static inline void pmic_arb_base_write(struct spmi_pmic_arb *pa,

				       u32 offset, u32 val)

{

	if (pa->ahb_bus_wa) {

		/* AHB bus register dummy read for workaround. */

		readl_relaxed(pa->cnfg + SPMI_PROTOCOL_IRQ_STATUS);

		/*

		 * Ensure that the read completes before initiating the

		 * subsequent register write.

		 */

		mb();

	}



	writel_relaxed(val, pa->wr_base + offset);

}
@@ -1343,6 +1358,9 @@ static int spmi_pmic_arb_probe(struct platform_device *pdev) 


	pa->ee = ee;



	pa->ahb_bus_wa = of_property_read_bool(pdev->dev.of_node,

					"qcom,enable-ahb-bus-workaround");



	pa->mapping_table = devm_kcalloc(&ctrl->dev, PMIC_ARB_MAX_PERIPHS - 1,

					sizeof(*pa->mapping_table), GFP_KERNEL);

	if (!pa->mapping_table) {