+
+static int tegra_io_rail_prepare(int id, unsigned long *request,
+ unsigned long *status, unsigned int *bit)
+{
+ unsigned long rate, value;
+ struct clk *clk;
+
+ *bit = id % 32;
+
+ /*
+ * There are two sets of 30 bits to select IO rails, but bits 30 and
+ * 31 are control bits rather than IO rail selection bits.
+ */
+ if (id > 63 || *bit == 30 || *bit == 31)
+ return -EINVAL;
+
+ if (id < 32) {
+ *status = IO_DPD_STATUS;
+ *request = IO_DPD_REQ;
+ } else {
+ *status = IO_DPD2_STATUS;
+ *request = IO_DPD2_REQ;
+ }
+
+ clk = clk_get_sys(NULL, "pclk");
+ if (IS_ERR(clk))
+ return PTR_ERR(clk);
+
+ rate = clk_get_rate(clk);
+ clk_put(clk);
+
+ pmc_write(DPD_SAMPLE_ENABLE, DPD_SAMPLE);
+
+ /* must be at least 200 ns, in APB (PCLK) clock cycles */
+ value = DIV_ROUND_UP(1000000000, rate);
+ value = DIV_ROUND_UP(200, value);
+ pmc_write(value, SEL_DPD_TIM);
+
+ return 0;
+}
+
+static int tegra_io_rail_poll(unsigned long offset, unsigned long mask,
+ unsigned long val, unsigned long timeout)
+{
+ unsigned long value;
+
+ timeout = jiffies + msecs_to_jiffies(timeout);
+
+ while (time_after(timeout, jiffies)) {
+ value = pmc_read(offset);
+ if ((value & mask) == val)
+ return 0;
+
+ usleep_range(250, 1000);
+ }
+
+ return -ETIMEDOUT;
+}
+
+static void tegra_io_rail_unprepare(void)
+{
+ pmc_write(DPD_SAMPLE_DISABLE, DPD_SAMPLE);
+}
+
+int tegra_io_rail_power_on(int id)
+{
+ unsigned long request, status, value;
+ unsigned int bit, mask;
+ int err;
+
+ err = tegra_io_rail_prepare(id, &request, &status, &bit);
+ if (err < 0)
+ return err;
+
+ mask = 1 << bit;
+
+ value = pmc_read(request);
+ value |= mask;
+ value &= ~IO_DPD_REQ_CODE_MASK;
+ value |= IO_DPD_REQ_CODE_OFF;
+ pmc_write(value, request);
+
+ err = tegra_io_rail_poll(status, mask, 0, 250);
+ if (err < 0)
+ return err;
+
+ tegra_io_rail_unprepare();
+
+ return 0;
+}
+
+int tegra_io_rail_power_off(int id)
+{
+ unsigned long request, status, value;
+ unsigned int bit, mask;
+ int err;
+
+ err = tegra_io_rail_prepare(id, &request, &status, &bit);
+ if (err < 0)
+ return err;
+
+ mask = 1 << bit;
+
+ value = pmc_read(request);
+ value |= mask;
+ value &= ~IO_DPD_REQ_CODE_MASK;
+ value |= IO_DPD_REQ_CODE_ON;
+ pmc_write(value, request);
+
+ err = tegra_io_rail_poll(status, mask, mask, 250);
+ if (err < 0)
+ return err;
+
+ tegra_io_rail_unprepare();
+
+ return 0;
+}