From: Archana Sriram <archana.sriram@xxxxxx>
Errata Id:i582
PER Domain reset issue after Domain-OFF/OSWR Wakeup.
Issue:
When Peripheral Power Domain (PER-PD) is woken up from OFF / OSWR
state while Core Power Domain (CORE-PD) is kept active, write or
read access to some internal memory (e.g., UART3 FIFO) does not
work correctly.
Workaround :
* Prevent PER from going off when CORE has not gone to off.
* When both CORE-PD and PER-PD goes into OSWR/OFF, PER-PD should be
brought to active before CORE-PD.This can be done by configuring a wakeup
dependency so that CORE-PD and PER-PD will wake up at the same time.
Acked-by: Tero Kristo <tero.kristo@xxxxxxxxx>
Tested-by: Eduardo Valentin <eduardo.valentin@xxxxxxxxx>
Tested-by: Westerberg Mika <ext-mika.1.westerberg@xxxxxxxxx>
[vishwanath.bs@xxxxxx: initial code and suggestions]
Signed-off-by: Vishwanath BS <vishwanath.bs@xxxxxx>
[nm@xxxxxx: forward ported to 2.6.37-rc2 and suggestions]
Signed-off-by: Nishanth Menon <nm@xxxxxx>
Signed-off-by: Archana Sriram <archana.sriram@xxxxxx>
---
arch/arm/mach-omap2/pm34xx.c | 41 +++++++++++++++-
arch/arm/mach-omap2/serial.c | 80 ++++++++++++++++++++++++++++++
arch/arm/plat-omap/include/plat/serial.h | 4 ++
3 files changed, 124 insertions(+), 1 deletions(-)
diff --git a/arch/arm/mach-omap2/pm34xx.c b/arch/arm/mach-omap2/pm34xx.c
index c7e2db0..218d0b0 100644
--- a/arch/arm/mach-omap2/pm34xx.c
+++ b/arch/arm/mach-omap2/pm34xx.c
@@ -84,6 +84,10 @@ static struct powerdomain *cam_pwrdm;
static int secure_ram_save_status;
static int secure_ram_saved;
+#define PER_WAKEUP_ERRATA_i582 (1 << 0)
+static u16 pm34xx_errata;
+#define IS_PM34XX_ERRATA(id) (pm34xx_errata & (id))
+
static inline void omap3_per_save_context(void)
{
omap_gpio_save_context();
@@ -371,7 +375,8 @@ void omap_sram_idle(void)
int mpu_next_state = PWRDM_POWER_ON;
int per_next_state = PWRDM_POWER_ON;
int core_next_state = PWRDM_POWER_ON;
- int core_prev_state, per_prev_state;
+ int core_prev_state = PWRDM_POWER_ON;
+ int per_prev_state = PWRDM_POWER_ON;
u32 sdrc_pwr = 0;
if (!_omap_sram_idle)
@@ -496,6 +501,23 @@ void omap_sram_idle(void)
omap3_per_restore_context();
omap_uart_resume_idle(2);
omap_uart_resume_idle(3);
+ if (IS_PM34XX_ERRATA(PER_WAKEUP_ERRATA_i582) &&
+ omap_uart_check_per_uarts_used() &&
+ (core_prev_state == PWRDM_POWER_ON) &&
+ (per_prev_state == PWRDM_POWER_OFF)) {
+ /*
+ * We dont seem to have a real recovery other than reset
+ * Errata i582:Alternative available here is to do a
+ * reboot OR go to per off/core off, we will just print
+ * and cause uart to be in an unstable state and
+ * continue on till we hit the next off transition.
+ * Reboot of the device due to this corner case is
+ * undesirable.
+ */
+ if (omap_uart_per_errata())
+ pr_err("%s: PER UART hit with Errata i582 "
+ "Corner case.\n", __func__);
+ }
}
/* Disable IO-PAD and IO-CHAIN wakeup */
@@ -1021,15 +1043,27 @@ void omap_push_sram_idle(void)
save_secure_ram_context_sz);
}
+static void pm_errata_configure(void)
+{
+ if (cpu_is_omap34xx()) {
+ pm34xx_errata |= PER_WAKEUP_ERRATA_i582;
+ if (cpu_is_omap3630() && (omap_rev() > OMAP3630_REV_ES1_1))
+ pm34xx_errata &= ~PER_WAKEUP_ERRATA_i582;
+ }
+}
+
static int __init omap3_pm_init(void)
{
struct power_state *pwrst, *tmp;
struct clockdomain *neon_clkdm, *per_clkdm, *mpu_clkdm, *core_clkdm;
+ struct clockdomain *wkup_clkdm;
int ret;
if (!cpu_is_omap34xx())
return -ENODEV;
+ pm_errata_configure();
+
printk(KERN_ERR "Power Management for TI OMAP3.\n");
/* XXX prcm_setup_regs needs to be before enabling hw
@@ -1067,6 +1101,7 @@ static int __init omap3_pm_init(void)
neon_clkdm = clkdm_lookup("neon_clkdm");
mpu_clkdm = clkdm_lookup("mpu_clkdm");
per_clkdm = clkdm_lookup("per_clkdm");
+ wkup_clkdm = clkdm_lookup("wkup_clkdm");
core_clkdm = clkdm_lookup("core_clkdm");
omap_push_sram_idle();
@@ -1077,6 +1112,10 @@ static int __init omap3_pm_init(void)
pm_idle = omap3_pm_idle;
omap3_idle_init();
+ /* Allow per to wakeup the system if errata is applicable */
+ if (IS_PM34XX_ERRATA(PER_WAKEUP_ERRATA_i582) && cpu_is_omap34xx())
+ clkdm_add_wkdep(per_clkdm, wkup_clkdm);
+
clkdm_add_wkdep(neon_clkdm, mpu_clkdm);
omap3_save_scratchpad_contents();
diff --git a/arch/arm/mach-omap2/serial.c b/arch/arm/mach-omap2/serial.c
index becf0e3..43c2ec4 100644
--- a/arch/arm/mach-omap2/serial.c
+++ b/arch/arm/mach-omap2/serial.c
@@ -273,6 +273,86 @@ static void omap_uart_restore_context(struct omap_uart_state *uart)
/* UART 16x mode */
serial_write_reg(uart, UART_OMAP_MDR1, 0x00);
}
+
+static inline int _is_per_uart(struct omap_uart_state *uart)
+{
+ if (cpu_is_omap34xx() && (uart->num == 2 || uart->num == 3))
+ return 1;
+ return 0;
+}
+
+int omap_uart_check_per_uarts_used(void)
+{
+ struct omap_uart_state *uart;
+
+ list_for_each_entry(uart, &uart_list, node) {
+ if (_is_per_uart(uart))
+ return 1;
+ }
+ return 0;
+}
+
+/*
+ * Errata i582 affects PER UARTS..Loop back test is done to
+ * check the UART state when the corner case is encountered
+ */
+static int omap_uart_loopback_test(struct omap_uart_state *uart)
+{
+ u8 loopbk_rhr = 0;
+
+ omap_uart_save_context(uart);
+ serial_write_reg(uart, UART_OMAP_MDR1, 0x7);
+ serial_write_reg(uart, UART_LCR, 0xBF); /* Config B mode */
+ serial_write_reg(uart, UART_DLL, uart->dll);
+ serial_write_reg(uart, UART_DLM, uart->dlh);
+ serial_write_reg(uart, UART_LCR, 0x0); /* Operational mode */
+ /* configure uart3 in UART mode */
+ serial_write_reg(uart, UART_OMAP_MDR1, 0x00); /* UART 16x mode */
+ serial_write_reg(uart, UART_LCR, 0x80);
+ /* Enable internal loop back mode by setting MCR_REG[4].LOOPBACK_EN */
+ serial_write_reg(uart, UART_MCR, 0x10);
+
+ /* write to THR,read RHR and compare */
+ /* Tx output is internally looped back to Rx input in loop back mode */
+ serial_write_reg(uart, UART_LCR_DLAB, 0x00);
+ /* Enables write to THR and read from RHR */
+ serial_write_reg(uart, UART_TX, 0xCC); /* writing data to THR */
+ /* reading data from RHR */
+ loopbk_rhr = (serial_read_reg(uart, UART_RX) & 0xFF);
+ if (loopbk_rhr == 0xCC) {
+ /* compare passes,try comparing with different data */
+ serial_write_reg(uart, UART_TX, 0x69);
+ loopbk_rhr = (serial_read_reg(uart, UART_RX) & 0xFF);
+ if (loopbk_rhr == 0x69) {
+ /* compare passes,reset UART3 and re-configure module */
+ omap_uart_reset(uart);
+ omap_uart_restore_context(uart);
+ return 0;
+ }
+ } else { /* requires warm reset */
+ return -ENODEV;
+ }
+ return 0;
+}
+
+int omap_uart_per_errata(void)
+{
+ struct omap_uart_state *uart;
+
+ /* For all initialised UART modules that are in PER domain
+ * do loopback test
+ */
+ list_for_each_entry(uart, &uart_list, node) {
+ if (_is_per_uart(uart)) {
+ if (omap_uart_loopback_test(uart))
+ return -ENODEV;
+ else
+ return 0;
+ }
+ }
+ return 0;
+}
+
#else
static inline void omap_uart_save_context(struct omap_uart_state *uart) {}
static inline void omap_uart_restore_context(struct omap_uart_state *uart) {}
diff --git a/arch/arm/plat-omap/include/plat/serial.h b/arch/arm/plat-omap/include/plat/serial.h
index 19145f5..81169b2 100644
--- a/arch/arm/plat-omap/include/plat/serial.h
+++ b/arch/arm/plat-omap/include/plat/serial.h
@@ -102,6 +102,10 @@ extern void omap_uart_prepare_suspend(void);
extern void omap_uart_prepare_idle(int num);
extern void omap_uart_resume_idle(int num);
extern void omap_uart_enable_irqs(int enable);
+#ifdef CONFIG_PM
+extern int omap_uart_per_errata(void);
+extern int omap_uart_check_per_uarts_used(void);
+#endif
#endif
#endif
--
1.6.3.3
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